i2c: Export the i2c_bus_type symbol

Export the root of the i2c bus so that PowerPC device tree code can
iterate over devices on the i2c bus.

Signed-off-by: Jon Smirl <jonsmirl@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 839d0ea..50cbab4 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -35,6 +35,8 @@
 #include <linux/sched.h>	/* for completion */
 #include <linux/mutex.h>
 
+extern struct bus_type i2c_bus_type;
+
 /* --- General options ------------------------------------------------	*/
 
 struct i2c_msg;