Staging: hv: storvsc: Cleanup error handling in storvsc_do_io()

Use standard Linux error codes.
Signed-off-by: NK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: NHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/hv/storvsc.c

@@ -454,7 +454,7 @@ int storvsc_do_io(struct hv_device *device,
 	stor_device = get_stor_device(device);
 
 	if (!stor_device)
-		return -2;
+		return -ENODEV;
 
 
 	request->device  = device;