At least the third rgmii port is available on 63169, so assume all are
available. Simplifies cpu vs. variant handling.

Signed-off-by: Jonas Gorski <jogo@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@45504 3c298f89-4303-0410-b956-a3cf2f4a3e73