vfio: ccw: add tracepoints for interesting error paths

Add some tracepoints so we can inspect what is not working as is should.

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.ibm.com>
Message-Id: <20180523025645.8978-5-bjsdjshi@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>