driver: Avoid possible accidental mismatch between ledc_clk_src_t & ledc_clk_cfg_t enum

ledc.h includes two similar enums, ledc_clk_src_t & ledc_clk_cfg_t.

The two enums do different things but there are two similar names: LEDC_REF_TICK / LEDC_USE_REF_TICK
and LEDC_APB_CLK / LEDC_USE_APB_CLK.

Because C will accept any enum or integer value for an enum argument, there's no easy way to check
the correct enum is passed without using static analysis.

To avoid accidental errors, make the numeric values for the two similarly named enums the same.,

Noticed when looking into https://github.com/espressif/esp-idf/issues/4476

components/driver/include/driver/ledc.h

@@ -46,18 +46,22 @@ typedef enum {
     LEDC_DUTY_DIR_MAX,
 } ledc_duty_direction_t;
 
-typedef enum  {
-    LEDC_REF_TICK = 0, /*!< LEDC timer clock divided from reference tick (1Mhz) */
-    LEDC_APB_CLK,      /*!< LEDC timer clock divided from APB clock (80Mhz) */
-} ledc_clk_src_t;
-
 typedef enum {
-    LEDC_AUTO_CLK,        /*!< The driver will automatically select the source clock(REF_TICK or APB) based on the giving resolution and duty parameter when init the timer*/  
+    LEDC_AUTO_CLK,        /*!< The driver will automatically select the source clock(REF_TICK or APB) based on the giving resolution and duty parameter when init the timer*/
     LEDC_USE_REF_TICK,    /*!< LEDC timer select REF_TICK clock as source clock*/
     LEDC_USE_APB_CLK,     /*!< LEDC timer select APB clock as source clock*/
     LEDC_USE_RTC8M_CLK,   /*!< LEDC timer select RTC8M_CLK as source clock. Only for low speed channels and this parameter must be the same for all low speed channels*/
 } ledc_clk_cfg_t;
 
+/* Note: Setting numeric values to match ledc_clk_cfg_t values are a hack to avoid collision with
+   LEDC_AUTO_CLK in the driver, as these enums have very similar names and user may pass
+   one of these by mistake. */
+typedef enum  {
+    LEDC_REF_TICK = LEDC_USE_REF_TICK, /*!< LEDC timer clock divided from reference tick (1Mhz) */
+    LEDC_APB_CLK = LEDC_USE_APB_CLK,  /*!< LEDC timer clock divided from APB clock (80Mhz) */
+} ledc_clk_src_t;
+
+
 typedef enum {
     LEDC_TIMER_0 = 0, /*!< LEDC timer 0 */
     LEDC_TIMER_1,     /*!< LEDC timer 1 */