net/9p: Add multi channel support.

This is needed for supporting multiple mount points.

We can find out the device names to be used with mount by checking

/sys/devices/virtio-pci/virtio*/device file

if the device file have value 9 then the specific virtio device can
be used for mounting.

ex:
 #cat /sys/devices/virtio-pci/virtio1/device
 9

now we can mount using
# mount -t 9p -o trans=virtio virtio1  /mnt/

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/include/linux/virtio_9p.h b/include/linux/virtio_9p.h
index 095e10d..7a615c3 100644
--- a/include/linux/virtio_9p.h
+++ b/include/linux/virtio_9p.h
@@ -6,6 +6,6 @@
 #include <linux/virtio_config.h>
 
 /* Maximum number of virtio channels per partition (1 for now) */
-#define MAX_9P_CHAN	1
+#define MAX_9P_CHAN	10
 
 #endif /* _LINUX_VIRTIO_9P_H */