Need to add mock stats in sanity test about ibm-powervs-block-csi-driver

[Madhan-SWE]

Sanity test failure logs

Running tool: /usr/local/go/bin/go test -timeout 30s -run ^TestSanity$ sigs.k8s.io/ibm-powervs-block-csi-driver/pkg/driver

=== RUN   TestSanity
I0215 15:02:23.014563   16967 driver.go:138] Listening for connections on address: &net.UnixAddr{Name:"/var/folders/4p/vdbppfnd5djb7c8w6nqhy6mw0000gn/T/sanity-ebs-csi3033423701/csi.sock", Net:"unix"}
Running Suite: CSI Driver Test Suite
====================================
Random Seed: 1644917543
Will run 119 of 119 specs

••E0215 15:02:23.044861   16967 driver.go:115] GRPC error: rpc error: code = InvalidArgument desc = Volume ID not provided
•E0215 15:02:23.045841   16967 driver.go:115] GRPC error: rpc error: code = InvalidArgument desc = Staging target not provided
•E0215 15:02:23.047273   16967 driver.go:115] GRPC error: rpc error: code = InvalidArgument desc = Staging target not provided
•E0215 15:02:23.048680   16967 driver.go:115] GRPC error: rpc error: code = InvalidArgument desc = Volume ID not provided
•E0215 15:02:23.049548   16967 driver.go:115] GRPC error: rpc error: code = InvalidArgument desc = Target path not provided
•E0215 15:02:23.050698   16967 driver.go:115] GRPC error: rpc error: code = InvalidArgument desc = Volume ID not provided
•E0215 15:02:23.051845   16967 driver.go:115] GRPC error: rpc error: code = InvalidArgument desc = Staging target not provided
•E0215 15:02:23.053572   16967 driver.go:115] GRPC error: rpc error: code = InvalidArgument desc = Volume capability not provided
•E0215 15:02:23.055330   16967 driver.go:115] GRPC error: rpc error: code = InvalidArgument desc = Volume ID not provided
•E0215 15:02:23.056919   16967 driver.go:115] GRPC error: rpc error: code = InvalidArgument desc = Staging target not provided
•E0215 15:02:23.058820   16967 driver.go:115] GRPC error: rpc error: code = InvalidArgument desc = Volume ID not provided
•E0215 15:02:23.060580   16967 driver.go:115] GRPC error: rpc error: code = InvalidArgument desc = VolumePath not provided
•panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x30 pc=0x20d7243]

goroutine 148 [running]:
sigs.k8s.io/ibm-powervs-block-csi-driver/pkg/driver.(*nodeService).NodeGetVolumeStats(0xc000735120, {0x2303720, 0x2426e80}, 0xc000632a50)
        /Users/madhankumar/work/csie2etest/prowFix/ibm-powervs-block-csi-driver/pkg/driver/node.go:399 +0x143
github.com/container-storage-interface/spec/lib/go/csi._Node_NodeGetVolumeStats_Handler.func1({0x26daea0, 0xc000631050}, {0x23a1760, 0xc000632a50})
        /Users/madhankumar/go/pkg/mod/github.com/container-storage-interface/[email protected]/lib/go/csi/csi.pb.go:6182 +0x78
sigs.k8s.io/ibm-powervs-block-csi-driver/pkg/driver.(*Driver).Run.func1({0x26daea0, 0xc000631050}, {0x23a1760, 0xc000632a50}, 0xc00032ebb8, 0x2257980)
        /Users/madhankumar/work/csie2etest/prowFix/ibm-powervs-block-csi-driver/pkg/driver/driver.go:113 +0x42
github.com/container-storage-interface/spec/lib/go/csi._Node_NodeGetVolumeStats_Handler({0x2426e80, 0xc000735100}, {0x26daea0, 0xc000631050}, 0xc000636720, 0x2563910)
        /Users/madhankumar/go/pkg/mod/github.com/container-storage-interface/[email protected]/lib/go/csi/csi.pb.go:6184 +0x138
google.golang.org/grpc.(*Server).processUnaryRPC(0xc0002e21c0, {0x27063b8, 0xc00030a680}, 0xc000638900, 0xc0006188a0, 0x34ad200, 0x0)
        /Users/madhankumar/go/pkg/mod/google.golang.org/[email protected]/server.go:1282 +0xccf
google.golang.org/grpc.(*Server).handleStream(0xc0002e21c0, {0x27063b8, 0xc00030a680}, 0xc000638900, 0x0)
        /Users/madhankumar/go/pkg/mod/google.golang.org/[email protected]/server.go:1616 +0xa2a
google.golang.org/grpc.(*Server).serveStreams.func1.2()
        /Users/madhankumar/go/pkg/mod/google.golang.org/[email protected]/server.go:921 +0x98
created by google.golang.org/grpc.(*Server).serveStreams.func1
        /Users/madhankumar/go/pkg/mod/google.golang.org/[email protected]/server.go:919 +0x294
FAIL    sigs.k8s.io/ibm-powervs-block-csi-driver/pkg/driver     0.683s


> Test run finished at 15/02/2022, 15:02:23 

[Madhan-SWE]

/assign