aufs: minor, pseudo keyword 'fallthrough'

Simply follows the mainline,
294f69e662d15 2019-10-11 compiler_attributes.h: Add 'fallthrough' pseudo keyword for switch/case use
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

fs/aufs/cpup.c

@@ -696,7 +696,7 @@ int cpup_entry(struct au_cp_generic *cpg, struct dentry *dst_parent,
 	case S_IFCHR:
 	case S_IFBLK:
 		AuDebugOn(!capable(CAP_MKNOD));
-		/*FALLTHROUGH*/
+		fallthrough;
 	case S_IFIFO:
 	case S_IFSOCK:
 		err = vfsub_mknod(h_dir, &h_path, mode, h_inode->i_rdev);

fs/aufs/hnotify.c

@@ -571,7 +571,7 @@ int au_hnotify(struct inode *h_dir, struct au_hnotify *hnotify, u32 mask,
 	case FS_MOVED_TO:
 		au_fset_hnjob(flags[AuHn_CHILD], XINO0);
 		au_fset_hnjob(flags[AuHn_CHILD], MNTPNT);
-		/*FALLTHROUGH*/
+		fallthrough;
 	case FS_CREATE:
 		AuDebugOn(!h_child_name);
 		break;

fs/aufs/opts.c

@@ -494,7 +494,7 @@ au_wbr_create_val(char *str, struct au_opt_wbr_create *create)
 			err = e;
 			break;
 		}
-		/*FALLTHROUGH*/
+		fallthrough;
 	case AuWbrCreate_MFS:
 	case AuWbrCreate_PMFS:
 		create->mfs_second = AUFS_MFS_DEF_SEC;
@@ -1226,7 +1226,7 @@ int au_opts_parse(struct super_block *sb, char *str, struct au_opts *opts)
 
 		case Opt_ignore:
 			pr_warn("ignored %s\n", opt_str);
-			/*FALLTHROUGH*/
+			fallthrough;
 		case Opt_ignore_silent:
 			skipped = 1;
 			err = 0;
@@ -1282,7 +1282,7 @@ static int au_opt_wbr_create(struct super_block *sb,
 	case AuWbrCreate_PMFSRR:
 	case AuWbrCreate_PMFSRRV:
 		sbinfo->si_wbr_mfs.mfsrr_watermark = create->mfsrr_watermark;
-		/*FALLTHROUGH*/
+		fallthrough;
 	case AuWbrCreate_MFS:
 	case AuWbrCreate_MFSV:
 	case AuWbrCreate_PMFS:
@@ -1502,7 +1502,7 @@ static int au_opt_br(struct super_block *sb, struct au_opt *opt,
 		/* Always goto add, not fallthrough */
 	case Opt_prepend:
 		opt->add.bindex = 0;
-		/* fallthrough */
+		fallthrough;
 	add: /* indented label */
 	case Opt_add:
 		err = au_br_add(sb, &opt->add,