bnxt_en: Zero pad firmware messages to 128 bytes.

For future compatibility, zero pad all messages that the driver sends
to the firmware to 128 bytes.  If these messages are extended in the
future with new byte enables, zero padding these messages now will
guarantee future compatibility.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>