bnx2x: Fix potential link issue In BCM8727 based boards

In BCM8727 based boards, setting default 10G link speed after link was
set to 1G may lead to link down issue. The problem was setting the right
value, but to the wrong registers

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>