mpi3mr: Cleaup setting of status in processing scsiio requests

More uniformly use mpi3mr_set_ccbstatus in mpi3mr_action_scsiio. The
routine mostly used it, but also has setting of status by hand. In those
cases where we want to error out the request, use this routine.

As part of this, move setting CAM_SIM_QUEUED later in the function to
when we're sure it's been queued. Remove the places we clear it before
this.

Sponsored by: Netflix
Reviewed by: mav, jhb
Differential Revision: https://reviews.freebsd.org/D42542