virtio: switch to 64 bit features

virtio: switch to 64 bit features

Switch to 64 bit features, which virtio 1.0 supports.

While legacy virtio only supports 32 bit features, it complains aloud
and quit when trying to setting > 32 bit features.

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Tested-by: Qian Xu <qian.q.xu@intel.com>
Reviewed-by: Tetsuya Mukawa <mukawa@igel.co.jp>
Tested-by: Tetsuya Mukawa <mukawa@igel.co.jp>
Acked-by: Huawei Xie <huawei.xie@intel.com>