bnxt_en: Introduce bnxt_get_hwrm_resp_addr & bnxt_get_hwrm_seq_id routines.

These routines will be enhanced in the subsequent patch to
return the 2nd firmware comm. channel's hwrm response address &
sequence id respectively.

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