bnxt_en: Add support for firmware updates for additional processors.

Add support to the Ethtool FLASHDEV command handler for additional
firmware types to cover all the on-chip processors.

Signed-off-by: Rob Swindell <rob.swindell@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>