bnxt_en: Consolidate firmware reset event logging.

Combine the three netdev_warn() calls into a single call, printed at
the NETIF_MSG_HW log level.

Reviewed-by: Vasundhara Volam <vasundhara-v.volam@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>