[PATCH] pm3386: add hook for setting MAC address

When we reset the pm3386, it loses its internally stored MAC addresses
that were programmed into it by the bootloader (and are used by the
hardware for the generation of PAUSE frames.)  Add a hook to allow
setting these addresses so that we can program them back by hand.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>