[BNX2]: Add support for remote PHY.

In blade servers, the Serdes PHY in 5708S can control the remote
copper PHY through autonegotiation on the backplane.  This patch adds
the logic to interface with the firmware to control the remote PHY
autonegotiation and to handle remote PHY link events.

When remote PHY is present, the 5708S Serdes device practically
becomes a copper device with full control over the 1000Base-T
link settings.
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>