bnx2x: Improve cl45 access methods

Instead of setting CL45 mode for every CL45 access, apply it 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>