azure: Add validation of resourceGroup option.

ResourceGroup can be set only on kind: Managed disks.

pkg/volume/azure_dd/azure_provision.go

@@ -17,6 +17,7 @@ limitations under the License.
 package azure_dd
 
 import (
+	"errors"
 	"fmt"
 	"strings"
 
@@ -145,6 +146,10 @@ func (p *azureDiskProvisioner) Provision(selectedNode *v1.Node, allowedTopologie
 		return nil, err
 	}
 
+	if resourceGroup != "" && kind != v1.AzureManagedDisk {
+		return nil, errors.New("StorageClass option 'resourceGroup' can be used only for managed disks")
+	}
+
 	// create disk
 	diskURI := ""
 	if kind == v1.AzureManagedDisk {