bnxt_en: Refactor _hwrm_send_message().

Add a new function bnxt_do_send_msg() to do essentially the same thing
with an additional paramter to silence error response messages.  All
current callers will set silent to false.

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