cifs: ignore auto and noauto options if given

In 24e0a1ef, the noauto and auto options were missed when migrating
to the new mount API. As a result, users with noauto in their fstab
mount options are now unable to mount cifs filesystems, as they'll
receive an "Unknown parameter" error.

This restores the old behaviour of ignoring noauto and auto if they're
given.

Fixes: 24e0a1ef ("cifs: switch to new mount api")
Signed-off-by: Adam Harvey <adam@adamharvey.name>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>