net/9p: remove virtio default hack and set appropriate bits instead

A few releases back a patch made virtio the default transport, however
it was done in a way which side-stepped the mechanism put in place to
allow for this selection.  This patch cleans that up while maintaining
virtio as the default transport.
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

net/9p/client.c

@@ -1011,9 +1011,6 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
 	if (err < 0)
 		goto destroy_tagpool;
 
-	if (!clnt->trans_mod)
-		clnt->trans_mod = v9fs_get_trans_by_name("virtio");
-
 	if (!clnt->trans_mod)
 		clnt->trans_mod = v9fs_get_default_trans();
 

net/9p/trans_fd.c

@@ -1048,7 +1048,7 @@ p9_fd_create(struct p9_client *client, const char *addr, char *args)
 static struct p9_trans_module p9_tcp_trans = {
 	.name = "tcp",
 	.maxsize = MAX_SOCK_BUF,
-	.def = 1,
+	.def = 0,
 	.create = p9_fd_create_tcp,
 	.close = p9_fd_close,
 	.request = p9_fd_request,

net/9p/trans_virtio.c

@@ -698,7 +698,7 @@ static struct p9_trans_module p9_virtio_trans = {
 	 * page in zero copy.
 	 */
 	.maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3),
-	.def = 0,
+	.def = 1,
 	.owner = THIS_MODULE,
 };