bnx2x: Added EEE support

This patch adds energy efficient energy support (802.3az) to bnx2x
boards with 84833 phys (and sufficiently new BC and external FW).

Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>