virtio_console: fix uapi header

commit 6407d75a upstream.

uapi should use __u32 not u32.
Fix a macro in virtio_console.h which uses u32.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>