smb: client: remove unnecessary checks in open_cached_dir()

Checks inside open_cached_dir() can be removed because if dir caching is
disabled then tcon->cfids is necessarily NULL. Therefore, all other checks
are redundant.

Signed-off-by: Henrique Carvalho <henrique.carvalho@suse.com>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Reviewed-by: Enzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>