bnxt_en: Add additional chip ID definitions.

Add additional chip definitions and macros for all supported chips.
Add a new macro BNXT_CHIP_P4_PLUS for the newer generation of chips and
use the macro to properly determine the features supported by these
newer chips.

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