MAINTAINERS: remove drivers/net/wan/cycx*

This driver was removed by commit 6fcdf4fa (wanrouter: delete now
orphaned header content, files/drivers).

Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Signed-off-by: David S. Miller <davem@davemloft.net>