fix(i2s): Check if pin is used before clearing bus

Author: P-R-O-C-H-Y

Diff for: libraries/ESP_I2S/src/ESP_I2S.cpp

@@ -719,9 +719,15 @@ bool I2SClass::end() {
 #if SOC_I2S_SUPPORTS_TDM
     case I2S_MODE_TDM:
 #endif
-      perimanClearPinBus(_mclk);
-      perimanClearPinBus(_bclk);
-      perimanClearPinBus(_ws);
+      if(_mclk >= 0) {
+        perimanClearPinBus(_mclk);
+      }
+      if(_bclk >= 0) {
+        perimanClearPinBus(_bclk);
+      }
+      if(_ws >= 0) {
+        perimanClearPinBus(_ws);
+      }
       if (_dout >= 0) {
         perimanClearPinBus(_dout);
       }