bnxt_en: Simplify error checking in the SR-IOV message forwarding functions.

There are 4 functions handling message forwarding for SR-IOV.  They
check for non-zero firmware response code and then return -1.  There
is no need to do this anymore.  The main messaging function will
now return standard error code.  Since we don't need to examine the
response, we can use the hwrm_send_message() variant which will
take the mutex automatically.

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