virtio_input: Improve freeze handling

When executing suspend to ram, if lacking the operations
to reset device and free unused buffers before deleting
a vq, resource leaks and inconsistent device status will
appear.

According to chapter "3.3.1 Driver Requirements: Device Cleanup:"
of virtio-specification:
  Driver MUST ensure a virtqueue isn’t live
  (by device reset) before removing exposed
  buffers.

Therefore, modify the virtinput_freeze function to reset the
device and delete the unused buffers before deleting the
virtqueue, just like virtinput_remove does.

Co-developed-by: Ying Xu <ying123.xu@samsung.com>
Signed-off-by: Ying Xu <ying123.xu@samsung.com>
Co-developed-by: Junnan Wu <junnan01.wu@samsung.com>
Signed-off-by: Junnan Wu <junnan01.wu@samsung.com>
Signed-off-by: Ying Gao <ying01.gao@samsung.com>
Message-Id: <20250812095118.3622717-1-ying01.gao@samsung.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>