fix(topokey): changing topology key to unique name

There are setups where nodename is different than the hostname.
The driver uses the nodename and tries to set the "kubernetes.io/hostname"
node label to the nodename. Which will fail if nodename is not same as
hostname. Here, changing the key to unique name so that the driver can set
that key as node label and also it can not modify/touch the existing node labels.

Signed-off-by: Pawan <pawan@mayadata.io>

pkg/zfs/volume.go

@@ -42,7 +42,7 @@ const (
 	// ZFSNodeKey will be used to insert Label in ZfsVolume CR
 	ZFSNodeKey string = "kubernetes.io/nodename"
 	// ZFSTopologyKey is supported topology key for the zfs driver
-	ZFSTopologyKey string = "kubernetes.io/hostname"
+	ZFSTopologyKey string = "openebs.io/nodename"
 	// ZFSStatusPending shows object has not handled yet
 	ZFSStatusPending string = "Pending"
 	// ZFSStatusReady shows object has been processed