The arm "virt" machine needs "virtio-blk-pci" for devices that get attached
via the "-cdrom" option. Since this is an optional device that might not
be available in the binary, we should check for the availability of this
device first before using it.

Message-Id: <20230525081016.1870364-3-thuth@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Thomas Huth <thuth@redhat.com>