ovl: cleanup d_real for negative

d_real() is never called with a negative dentry.  So remove the
d_is_negative() check (which would never trigger anyway, since d_is_reg()
returns false for a negative dentry).
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/super.c

@@ -81,9 +81,6 @@ static struct dentry *ovl_d_real(struct dentry *dentry,
 		goto bug;
 	}
 
-	if (d_is_negative(dentry))
-		return dentry;
-
 	if (open_flags) {
 		err = ovl_open_maybe_copy_up(dentry, open_flags);
 		if (err)