vsock/virtio: free packets during the socket release

[ Upstream commit ac03046ece2b158ebd204dfc4896fd9f39f0e6c8 ]

When the socket is released, we should free all packets
queued in the per-socket list in order to avoid a memory
leak.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>