VSOCK: fix loopback on big-endian systems

The dst_cid and src_cid are 64 bits, therefore 64 bit accessors should be
used, and in fact in virtio_transport_common.c only 64 bit accessors are
used. Using 32 bit accessors for 64 bit values breaks big endian systems.

This patch fixes a wrong use of le32_to_cpu in virtio_transport_send_pkt.

Fixes: b9116823

 ("VSOCK: add loopback to virtio_transport")

Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>