vfio-ccw: Fix memory leak and don't call cp_free in cp_init

We don't set cp->initialized to true so calling cp_free
will just return and not do anything.

Also fix a memory leak where we fail to free a ccwchain
on an error.

Fixes: 812271b9 ("s390/cio: Squash cp_free() and cp_unpin_free()")
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Message-Id: <3173c4216f4555d9765eb6e4922534982bc820e4.1562854091.git.alifm@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>