s390x: Add individual loadparm assignment to CCW device

s390x: Add individual loadparm assignment to CCW device

Add a loadparm property to the VirtioCcwDevice object so that different
loadparms can be defined on a per-device basis for CCW boot devices.

The machine/global loadparm is still supported. If both a global and per-device
loadparm are defined, the per-device value will override the global value for
that device, but any other devices that do not specify a per-device loadparm
will still use the global loadparm.

It is invalid to assign a loadparm to a non-boot device.

Signed-off-by: Jared Rossi <jrossi@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20241020012953.1380075-15-jrossi@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>