Set gic-version=max for aarch64 qemu 'machine' arg

This is needed for qemu to run on the new aarch64 worker hosts,
per https://bugzilla.redhat.com/show_bug.cgi?id=1661976 .

Signed-off-by: Adam Williamson <awilliam@redhat.com>

templates.fif.json

@@ -36,7 +36,7 @@
                 "QEMU": "aarch64",
                 "QEMUCPU": "host",
                 "QEMUCPUS": "2",
-                "QEMUMACHINE": "virt",
+                "QEMUMACHINE": "virt,gic-version=max",
                 "QEMURAM": 3072,
                 "QEMU_VIRTIO_RNG": "1",
                 "SERIALDEV": "ttyAMA0",