[PATCH] PPC 44x EMAC driver: add 440SPe support

For some reason, the hardware designers made the polarity of one bit
in the 440SPe's PHY interface register the opposite of all other PPC
440 chips.  To handle this, abstract our access to this bit and do the
right thing based on the configured CPU type.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Eugene Surovegin <ebs@ebshome.net>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>