mm/zsmalloc.c: fix fall-through annotation

Replace "fallthru" with a proper "fall through" annotation.

This fix is part of the ongoing efforts to enabling
-Wimplicit-fallthrough

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Gustavo A. R. Silva <[email protected]>
Reviewed-by: Sergey Senozhatsky <[email protected]>
Cc: Minchan Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/zsmalloc.c

@@ -418,7 +418,7 @@ static void *zs_zpool_map(void *pool, unsigned long handle,
 	case ZPOOL_MM_WO:
 		zs_mm = ZS_MM_WO;
 		break;
-	case ZPOOL_MM_RW: /* fallthru */
+	case ZPOOL_MM_RW: /* fall through */
 	default:
 		zs_mm = ZS_MM_RW;
 		break;