bnx2x: Fix generic option settings

When user tried to change generic options using "ethtool -s" command, while SFP
module is plugged out or during module detection, the command would have failed
with "Unsupported port type" message. The fix is to ignore the port option in
case it's same as the current port configuration.

Signed-off-by: Yaniv Rosner <yanivr@broadcom.com>
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>