[PATCH] watchdog: wdt977: Mark expected switch fall-through

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

Mark switch cases where we are expecting to fall through.

This patch fixes the following warning (Building: arm):

drivers/watchdog/wdt977.c: In function ‘wdt977_ioctl’:
  LD [M]  drivers/media/platform/vicodec/vicodec.o
drivers/watchdog/wdt977.c:400:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
   wdt977_keepalive();
   ^~~~~~~~~~~~~~~~~~
drivers/watchdog/wdt977.c:403:2: note: here
  case WDIOC_GETTIMEOUT:
  ^~~~

Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
---
 drivers/watchdog/wdt977.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/watchdog/wdt977.c b/drivers/watchdog/wdt977.c
index 567005d7598e..5c52c73e1839 100644
--- a/drivers/watchdog/wdt977.c
+++ b/drivers/watchdog/wdt977.c
@@ -398,7 +398,7 @@ static long wdt977_ioctl(struct file *file, unsigned int cmd,
 			return -EINVAL;
 
 		wdt977_keepalive();
-		/* Fall */
+		/* Fall through */
 
 	case WDIOC_GETTIMEOUT:
 		return put_user(timeout, uarg.i);
-- 
2.22.0