driver model: increase BUS_ID_SIZE to 20

From Ben Collins, for the sake of ieee1394, so the 64-bit (16 char) GUID
can be used for the bus_id. 

include/linux/device.h

@@ -35,7 +35,7 @@
 #define DEVICE_NAME_SIZE	50
 #define DEVICE_NAME_HALF	__stringify(20)	/* Less than half to accommodate slop */
 #define DEVICE_ID_SIZE		32
-#define BUS_ID_SIZE		16
+#define BUS_ID_SIZE		20
 
 
 enum {