bnxt_en: Store the running firmware version code.

We currently only store the firmware version as a string for ethtool
and devlink info.  Store it also as a version code.  The next 2
patches will need to check the firmware major version to determine
some workarounds.

We also use the 16-bit firmware version fields if the firmware is newer
and provides the 16-bit fields.

Reviewed-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>