smb: client: get rid of dfs naming in automount code

Automount code will handle both DFS links and reparse mount points.

Also, get rid of BUG_ON() in cifs_release_automount_timer() while
we're at it.

Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>