refactoring enum declaration

lv_objx/lv_sw.h

@@ -46,12 +46,13 @@ typedef struct
     uint8_t changed   :1;           /*Indicates the switch explicitly changed by drag*/
 } lv_sw_ext_t;
 
-typedef enum {
+enum {
     LV_SW_STYLE_BG,
     LV_SW_STYLE_INDIC,
     LV_SW_STYLE_KNOB_OFF,
     LV_SW_STYLE_KNOB_ON,
-} lv_sw_style_t;
+};
+typedef uint8_t lv_sw_style_t;
 
 /**********************
  * GLOBAL PROTOTYPES