ADD I2C BUS device type

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2130 bbd45198-f89e-11dd-88c7-29a3b14d5316

include/rtdef.h

@@ -628,7 +628,8 @@ enum rt_device_class_type
     RT_Device_Class_RTC,                            /**< RTC device                                 */
     RT_Device_Class_Sound,                          /**< Sound device                               */
     RT_Device_Class_Graphic,                        /**< Graphic device                             */
-    RT_Device_Class_I2C,                            /**< I2C device                                 */
+    RT_Device_Class_I2CBUS,                         /**< I2C bus device                                 */
+    RT_Device_Class_I2CDevice,                      /**< I2C device                                 */
     RT_Device_Class_USBDevice,                      /**< USB slave device                           */
     RT_Device_Class_USBHost,                        /**< USB host bus                               */
     RT_Device_Class_SPIBUS,                         /**< SPI bus device                             */