bnxt_en: Add RESET_FW state logic to bnxt_fw_reset_task().

This state handles driver initiated chip reset during error recovery.
Only the master function will perform this step during error recovery.
The next patch will add code to initiate this reset from the master
function.

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