ledc: Add ledc_fade_stop API to support stopping the fade operation.

Note that ESP32 cannot support this new feature.

components/soc/esp32s3/include/soc/Kconfig.soc_caps.in

@@ -83,6 +83,10 @@ config SOC_LEDC_TIMER_BIT_WIDE_NUM
     int
     default 14
 
+config SOC_LEDC_SUPPORT_FADE_STOP
+    bool
+    default y
+
 config SOC_MPU_CONFIGURABLE_REGIONS_SUPPORTED
     bool
     default n

components/soc/esp32s3/include/soc/ledc_caps.h

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2019-2021 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2019-2022 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -13,6 +13,7 @@ extern "C" {
 #define SOC_LEDC_SUPPORT_XTAL_CLOCK  (1)
 #define SOC_LEDC_CHANNEL_NUM 8
 #define SOC_LEDC_TIMER_BIT_WIDE_NUM  (14)
+#define SOC_LEDC_SUPPORT_FADE_STOP   (1)
 
 #ifdef __cplusplus
 }