MIPS: BCM63xx: Add integrated ethernet mac support.

Signed-off-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>