bnx2x: Adding bnx2x_link

This patch is int the new bnx2x_link files (C and H). The files are
still not used in this patch, only in the next one so the patch will
be small enough for the mailing list.

Signed-off-by: Yaniv Rosner <yanivr@broadcom.com>
Signed-off-by: Eilong Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>