cifs: add files to host new mount api

This will make it easier in the future, but also will allow us to
shrink connect.c which is getting too big, and harder to read

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>