In order to support subchannels pass-through, we introduce a s390
subchannel device called "s390-ccw" to hold the real subchannel info.
The s390-ccw devices inherit from the abstract CcwDevice which connect
to the existing virtual-css-bus.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Message-Id: <20170517004813.58227-7-bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>