bnx2x: BCM8481 LED4 instead of LASI

The BCM8481 does not generate LASI interrupt for 10M, 100M and 1G link, so we
are using LED4 output as the interrupt input to the 57711. This requires some
adaptation in the link interrupt routines

Signed-off-by: Yaniv Rosner <yanivr@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>