Staging: hv: storvsc: Do not aquire an unnecessary reference on stor_device

On entry into storvsc_on_io_completion() we have already acquired a reference
on the stor_device; there is no need to acquire an additional reference here.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/hv/storvsc.c

@@ -232,9 +232,7 @@ static void storvsc_on_io_completion(struct hv_device *device,
 	struct storvsc_device *stor_device;
 	struct vstor_packet *stor_pkt;
 
-	stor_device = must_get_stor_device(device);
-	if (!stor_device)
-		return;
+	stor_device = (struct storvsc_device *)device->ext;
 
 	stor_pkt = &request->vstor_packet;
 
@@ -279,7 +277,6 @@ static void storvsc_on_io_completion(struct hv_device *device,
 		wake_up(&stor_device->waiting_to_drain);
 
 
-	put_stor_device(device);
 }
 
 static void storvsc_on_receive(struct hv_device *device,