fix: get zone panic

[andyzhangx]

What type of PR is this?

/kind bug

What this PR does / why we need it:

fix: get zone panic

I0330 02:55:06.555100       1 utils.go:78] GRPC request: {}
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0xc8 pc=0x184be5b]

goroutine 181 [running]:
sigs.k8s.io/cloud-provider-azure/pkg/provider.(*Cloud).GetZone(0xc00064ea80, {0xc000905320?, 0xc00058a680?})
        /mnt/vss/_work/1/go/src/sigs.k8s.io/azuredisk-csi-driver/vendor/sigs.k8s.io/cloud-provider-azure/pkg/provider/azure_zones.go:179 +0x2db
sigs.k8s.io/azuredisk-csi-driver/pkg/azuredisk.(*Driver).NodeGetInfo(0xc00091a000, {0x205aa20, 0xc000905050}, 0x253a955?)
        /mnt/vss/_work/1/go/src/sigs.k8s.io/azuredisk-csi-driver/pkg/azuredisk/nodeserver.go:336 +0x13b
github.com/container-storage-interface/spec/lib/go/csi._Node_NodeGetInfo_Handler.func1({0x205aa20, 0xc000905050}, {0x1c21220?, 0xc0004302e0})
        /mnt/vss/_work/1/go/src/sigs.k8s.io/azuredisk-csi-driver/vendor/github.com/container-storage-interface/spec/lib/go/csi/csi.pb.go:6238 +0x72
sigs.k8s.io/azuredisk-csi-driver/pkg/csi-common.logGRPC({0x205aa20, 0xc000905050}, {0x1c21220?, 0xc0004302e0?}, 0xc000430300, 0xc00038a420)
        /mnt/vss/_work/1/go/src/sigs.k8s.io/azuredisk-csi-driver/pkg/csi-common/utils.go:80 +0x409
github.com/container-storage-interface/spec/lib/go/csi._Node_NodeGetInfo_Handler({0x1d60b60?, 0xc00091a000}, {0x205aa20, 0xc000905050}, 0xc000518300, 0x1e9eba8)
        /mnt/vss/_work/1/go/src/sigs.k8s.io/azuredisk-csi-driver/vendor/github.com/container-storage-interface/spec/lib/go/csi/csi.pb.go:6240 +0x135
google.golang.org/grpc.(*Server).processUnaryRPC(0xc0003761e0, {0x205aa20, 0xc000904f90}, {0x20646e0, 0xc00050d6c0}, 0xc0009265a0, 0xc0005ef770, 0x2ee7548, 0x0)
        /mnt/vss/_work/1/go/src/sigs.k8s.io/azuredisk-csi-driver/vendor/google.golang.org/grpc/server.go:1343 +0xe03
google.golang.org/grpc.(*Server).handleStream(0xc0003761e0, {0x20646e0, 0xc00050d6c0}, 0xc0009265a0)
        /mnt/vss/_work/1/go/src/sigs.k8s.io/azuredisk-csi-driver/vendor/google.golang.org/grpc/server.go:1737 +0xc4c
google.golang.org/grpc.(*Server).serveStreams.func1.1()
        /mnt/vss/_work/1/go/src/sigs.k8s.io/azuredisk-csi-driver/vendor/google.golang.org/grpc/server.go:986 +0x86
created by google.golang.org/grpc.(*Server).serveStreams.func1 in goroutine 198
        /mnt/vss/_work/1/go/src/sigs.k8s.io/azuredisk-csi-driver/vendor/google.golang.org/grpc/server.go:997 +0x145

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

fix: get zone panic

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

fix: get zone panic

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andyzhangx

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[nilo19]

/lgtm