greybus: gb_operation: drop operation refcount on cancel

An extra reference is taken out on an operation in
gb_operation_request_send(). If the response never arrives, we need to
put back the reference.
Signed-off-by: Perry Hung <perry@leaflabs.com>
Tested-by: Mitchell Tasman <tasman@leaflabs.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/operation.c

@@ -895,6 +895,7 @@ void gb_operation_cancel(struct gb_operation *operation, int errno)
 		gb_message_cancel(operation->request);
 		gb_message_cancel(operation->response);
 	}
+	gb_operation_put(operation);
 }
 
 /**