vfio-ccw: allow non-prefetch ORBs

vfio-ccw: allow non-prefetch ORBs

Remove the explicit prefetch check when using vfio-ccw devices.
This check does not trigger in practice as all Linux channel programs
are intended to use prefetch.

Newer Linux kernel versions do not require to force the PFCH flag with
vfio-ccw devices anymore.

Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Message-Id: <20200512181535.18630-2-jrossi@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>