greybus: operation: fix up sparse warning

gb_connection_recv_request should be static, so mark it as such.

Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
diff --git a/drivers/staging/greybus/operation.c b/drivers/staging/greybus/operation.c
index aaac037..d973b57 100644
--- a/drivers/staging/greybus/operation.c
+++ b/drivers/staging/greybus/operation.c
@@ -616,8 +616,9 @@
  * This is called in interrupt context, so just copy the incoming
  * data into the request buffer and handle the rest via workqueue.
  */
-void gb_connection_recv_request(struct gb_connection *connection,
-	u16 operation_id, u8 type, void *data, size_t size)
+static void gb_connection_recv_request(struct gb_connection *connection,
+				       u16 operation_id, u8 type, void *data,
+				       size_t size)
 {
 	struct gb_operation *operation;