livenessprobe fails for controller only CSI driver

[sarjeet2013]

livenessprobe can be integrate to CSI driver which only implement Controller and Identity service, but no NodeServer service.

The following is making rpc call which is being implemented in NodeServer. We should make liveness probe universally common for CSI driver to only depend on Identity Service rpc calls.

https://github.com/kubernetes-csi/livenessprobe/blob/master/cmd/main.go#L56:
csiDriverNodeID, err := csiConn.NodeGetId(ctx)

Here is the log when integrated it to controller:

I1030 04:17:27.965740 1 main.go:109] Serving requests to /healthz on: 0.0.0.0:9809
I1030 04:17:40.913574 1 main.go:82] Request: /healthz from: 172.17.0.1:40302
I1030 04:17:40.913607 1 main.go:72] Attempting to open a gRPC connection with: /var/lib/csi/sockets/pluginproxy/csi.sock
I1030 04:17:40.913624 1 connection.go:70] Connecting to /var/lib/csi/sockets/pluginproxy/csi.sock
I1030 04:17:40.936761 1 connection.go:97] Still trying, connection is CONNECTING
I1030 04:17:40.937903 1 connection.go:94] Connected
I1030 04:17:40.937922 1 main.go:47] Calling CSI driver to discover driver name.
I1030 04:17:40.937933 1 connection.go:150] GRPC call: /csi.v0.Identity/GetPluginInfo
I1030 04:17:40.937943 1 connection.go:151] GRPC request:
I1030 04:17:40.950593 1 connection.go:153] GRPC response: name:"com.mapr.csi-kdf" vendor_version:"0.3.0"
I1030 04:17:40.950671 1 connection.go:154] GRPC error:
I1030 04:17:40.950680 1 main.go:52] CSI driver name: "com.mapr.csi-kdf"
I1030 04:17:40.950690 1 main.go:55] Calling CSI driver to discover node ID.
I1030 04:17:40.950699 1 connection.go:150] GRPC call: /csi.v0.Node/NodeGetId
I1030 04:17:40.950706 1 connection.go:151] GRPC request:
I1030 04:17:40.951186 1 connection.go:153] GRPC response:
I1030 04:17:40.951226 1 connection.go:154] GRPC error: rpc error: code = Unimplemented desc = unknown service csi.v0.Node
I1030 04:17:40.951289 1 main.go:95] Health check failed with: rpc error: code = Unimplemented desc = unknown service csi.v0.Node.

@sbezverk As discussed in #wg-csi, Let me know if there are additional information required for it?