ESP32 i2s: mclk_multiple=384 only when mclk pin is defined

Author: pschatzmann

src/AudioI2S/I2SESP32V1.h

@@ -207,7 +207,7 @@ class I2SDriverESP32V1 {
       if (cfg.mclk_multiple > 0){
         clk_cfg.mclk_multiple = cfg.mclk_multiple;
       } else {
-        if (cfg.bits_per_sample == 24) {
+        if (pin_mck!=-1 && cfg.bits_per_sample == 24) {
           // mclk_multiple' should be the multiple of 3 while using 24-bit
           clk_cfg.mclk_multiple = I2S_MCLK_MULTIPLE_384;
           LOGI("mclk_multiple=384");