Added method to change the ledc PWM frequency programmatically (#5003)

Added method to change the ledc PWM frequence programmatically
Returning frequency from ledcChangeFrequency

Author: iTacco

Diff for: cores/esp32/esp32-hal-ledc.c

@@ -318,3 +318,12 @@ void ledcDetachPin(uint8_t pin)
 {
     pinMatrixOutDetach(pin, false, false);
 }
+
+double ledcChangeFrequency(uint8_t chan, double freq, uint8_t bit_num)
+{
+    if (chan > 15) {
+        return 0;
+    }
+    double res_freq = _ledcSetupTimerFreq(chan, freq, bit_num);
+    return res_freq;
+}

Diff for: cores/esp32/esp32-hal-ledc.h

@@ -35,6 +35,7 @@ uint32_t    ledcRead(uint8_t channel);
 double      ledcReadFreq(uint8_t channel);
 void        ledcAttachPin(uint8_t pin, uint8_t channel);
 void        ledcDetachPin(uint8_t pin);
+double      ledcChangeFrequency(uint8_t channel, double freq, uint8_t resolution_bits);
 
 
 #ifdef __cplusplus