infiniband: bnxt_re: qplib: Check the return value of send_message

In bnxt_qplib_map_tc2cos(), bnxt_qplib_rcfw_send_message() can return an
error value but it is lost. Propagate this error to the callers.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Acked-By: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>