Added q35 machine type on multi_disk config file

BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1400385Signed-off-by: NJing Zhao <jinzhao@redhat.com>

qemu/tests/cfg/multi_disk.cfg

@@ -53,6 +53,8 @@
             stg_params = "drive_format:ide,scsi,virtio,scsi-hd,usb2"
             Host_RHEL:
                 stg_params = "drive_format:ide,virtio,scsi-hd,usb2"
+                q35:
+                    stg_params = "drive_format:ahci,virtio,scsi-hd,usb2"
             pseries:
                 stg_image_num = 3
                 stg_params = "drive_format:virtio,scsi-hd,usb2"