mips: annotate implicit fall throughs

There is a plan to build the kernel with -Wimplicit-fallthrough and
these places in the code produced warnings. Fix them up.

This patch produces no change in behaviour, but should be reviewed in
case these are actually bugs not intentional fallthoughs.

Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Kees Cook <keescook@google.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
index 96d666a..d0b64df 100644
--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -1280,6 +1280,7 @@ static void probe_pcache(void)
 
 	case CPU_VR4133:
 		write_c0_config(config & ~VR41_CONF_P4K);
+		/* fall through */
 	case CPU_VR4131:
 		/* Workaround for cache instruction bug of VR4131 */
 		if (c->processor_id == 0x0c80U || c->processor_id == 0x0c81U ||
@@ -1527,6 +1528,7 @@ static void probe_pcache(void)
 			c->dcache.flags |= MIPS_CACHE_PINDEX;
 			break;
 		}
+		/* fall through */
 	default:
 		if (has_74k_erratum || c->dcache.waysize > PAGE_SIZE)
 			c->dcache.flags |= MIPS_CACHE_ALIASES;