isdn_common: Mark expected switch fall-throughs

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

This patch fixes the following warnings:

drivers/isdn/i4l/isdn_common.c: In function ‘isdn_wildmat’:
drivers/isdn/i4l/isdn_common.c:173:5: warning: this statement may fall through [-Wimplicit-fallthrough=]

    p++;
    ~^~

drivers/isdn/i4l/isdn_common.c:174:3: note: here
default:
^~~~~~~
CC [M] drivers/leds/leds-lp8788.o
CC [M] drivers/gpu/drm/amd/amdgpu/../powerplay/smumgr/smu10_smumgr.o
drivers/isdn/i4l/isdn_common.c: In function ‘isdn_status_callback’:
drivers/isdn/i4l/isdn_common.c:729:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
if (divert_if)

      ^

drivers/isdn/i4l/isdn_common.c:732:2: note: here
default:
^~~~~~~

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.

---
 drivers/isdn/i4l/isdn_common.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

index 6a5b3f00f9ad..74ee00f5b310 100644
@@ -166,11 +166,9 @@ isdn_wildmat(char *s, char *p)
 	for (; *p; s++, p++)
 		switch (*p) {
 		case '\\':
-			/*
-			 * Literal match with following character,
-			 * fall through.
-			 */
+			/* Literal match with following character. */
 			p++;
+			/* fall through */
 		default:
 			if (*s != *p)
 				return (*s == '\0') ? 2 : 1;

@@ -729,6 +727,7 @@ isdn_status_callback(isdn_ctrl *c)
 		if (divert_if)
 			return (divert_if->stat_callback(c));
 #endif /* CONFIG_ISDN_DIVERSION */
+		/* fall through */
 	default:
 		return -1;
 	}

2.20.1

From: "Gustavo A. R. Silva" <[email protected]>
Date: Wed, 20 Feb 2019 14:25:26 -0600

Applied.

Thanks, Dave.

I wonder if you can take this one too:

https://lore.kernel.org/lkml/20190129180612.GA28650@embeddedor/

--
Gustavo