The m68k QEMU virt machine doesn't use devicetree, yet, so
allow it to create virtio-mmio instances via platform data.
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Reviewed-by: Angelo Dureghello <angelo@kernel-space.org>
Signed-off-by: Daniel Palmer <daniel@thingy.jp>
