[PATCH] xen, fbfront: mark expected switch fall-through

["Gustavo A. R. Silva" <gustavo@embeddedor.com>]

In preparation to enabling -Wimplicit-fallthrough, mark switch
cases where we are expecting to fall through.

This patch fixes the following warning:

drivers/video/fbdev/xen-fbfront.c: In function ‘xenfb_backend_changed’:
drivers/video/fbdev/xen-fbfront.c:678:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (dev->state = XenbusStateClosed)
      ^
drivers/video/fbdev/xen-fbfront.c:681:2: note: here
  case XenbusStateClosing:
  ^~~~

Warning level 3 was used: -Wimplicit-fallthrough=3

Notice that, in this particular case, the code comment is modified
in accordance with what GCC is expecting to find.

This patch is part of the ongoing efforts to enable
-Wimplicit-fallthrough.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/video/fbdev/xen-fbfront.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/xen-fbfront.c b/drivers/video/fbdev/xen-fbfront.c
index 6a4bbc9e1fb0..a3d6b6db221b 100644
--- a/drivers/video/fbdev/xen-fbfront.c
+++ b/drivers/video/fbdev/xen-fbfront.c
@@ -677,7 +677,7 @@ static void xenfb_backend_changed(struct xenbus_device *dev,
 	case XenbusStateClosed:
 		if (dev->state = XenbusStateClosed)
 			break;
-		/* Missed the backend's CLOSING state -- fallthrough */
+		/* fall through - Missed the backend's CLOSING state. */
 	case XenbusStateClosing:
 		xenbus_frontend_closed(dev);
 		break;
-- 
2.21.0