fs_enet: Add fixed-phy support for fs_enet

This patch adds support to use the fixed-link property of an ethernet node
to fs_enet for the CONFIG_PPC_CPM_NEW_BINDING case.

Signed-off-by: Jochen Friedrich <jochen@scram.de>
Acked-by: Jeff Garzik <jeff@garzik.org>
Acked-by: Vitali Bordug <vitb@kernel.crashing.org>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>