bnx2x: add support for retrieving dcb peer configuration

This patch adds support to the bnx2x for retrieving dcb peer (remote)
configuration from the embedded DCBX stack.

Signed-off-by: Shmulik Ravid <shmulikr@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>