bnx2x: Remove unneeded setting of XAUI low power to BCM8727

Remove unneeded setting of XAUI low power to BCM8727. This was required
only in older microcode which is not in the field.

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>