This will allow us to attach various properties specific to virtual
monitors in the future.

Note that we don't export an EDID property for "Virtual" connectors.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>