virtio: get rid of redundant VIRTIO_ID_9P definition

VIRTIO_ID_9P is already defined in include/linux/virtio_9p.h
so use that definition instead.

Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index 53c139d..ea1e3da 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -334,8 +334,6 @@
 	}
 }
 
-#define VIRTIO_ID_9P 9
-
 static struct virtio_device_id id_table[] = {
 	{ VIRTIO_ID_9P, VIRTIO_DEV_ANY_ID },
 	{ 0 },