aufs: bugfix, opts: Fix missing break statement

Add missing break statement for case Opt_wsum in au_opt_simple.
Signed-off-by: He Zhe <zhe.he@windriver.com>
See-also: https://www.mail-archive.com/aufs-users@lists.sourceforge.net/msg05684.html
(cherry picked from commit 9e7d29356ab57fa5db7e92e51267176e50c1497c)

fs/aufs/opts.c

@@ -1373,6 +1373,7 @@ static int au_opt_simple(struct super_block *sb, struct au_opt *opt,
 	case Opt_wsum:
 		au_opt_clr(sbinfo->si_mntflags, SUM);
 		au_opt_set(sbinfo->si_mntflags, SUM_W);
+		break;
 	case Opt_nosum:
 		au_opt_clr(sbinfo->si_mntflags, SUM);
 		au_opt_clr(sbinfo->si_mntflags, SUM_W);