cifs: Fix return value in __update_cache_entry

copy_ref_data() may return error, it should be
returned to upstream caller.

Fixes: 03535b72873b ("cifs: Avoid doing network I/O while holding cache lock")
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>

fs/cifs/dfs_cache.c

@@ -592,7 +592,7 @@ static int __update_cache_entry(const char *path,
 
 	kfree(th);
 
-	return 0;
+	return rc;
 }
 
 static int get_dfs_referral(const unsigned int xid, struct cifs_ses *ses,