bnx2x: Utilize FW 7.13.15.0.

Commit 97a27d6d6e8d "bnx2x: Add FW 7.13.15.0" added said .bin FW to
linux-firmware tree. This FW addresses few important issues in the earlier
FW release.
This patch incorporates FW 7.13.15.0 in the bnx2x driver.

Signed-off-by: Sudarsana Reddy Kalluru <skalluru@marvell.com>
Signed-off-by: Ariel Elior <aelior@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>