bnx2x: Adjust BCM8726 module detection settings

Move BCM8726 module detection code into a separate function to be called only once during initialization.

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>