bnx2x: Fix potential link issue of BCM8073/BCM8727

Fix potential link issue caused by insufficient delay time during SPIROM
load of BCM8073/BCM8727

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>