IB/rxe: Generate a completion for all failed work requests

Change do_complete() such that an error completion is not only
generated if a QP is in the error state but also if a work request
failed.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Andrew Boyer <andrew.boyer@dell.com>
Cc: Moni Shoua <monis@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>