The logic behind the expansion of DFS referrals is now extracted from
cifs_mount into a new static function, expand_dfs_referral.  This will
reduce duplicate code in upcoming commits.
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSean Finney <seanius@seanius.net>
Signed-off-by: NPavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: NSteve French <sfrench@us.ibm.com>