cifs: make use of cap_unix(ses) in cifs_reconnect_tcon()

cap_unix(ses) defaults to false for SMB2.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>