fix(uart): using uart number as argument instead

Author: SuGlider

cores/esp32/HardwareSerial.cpp

@@ -619,9 +619,12 @@ bool HardwareSerial::setMode(SerialMode mode) {
 // Note: CLK_SRC_PLL Freq depends on the SoC - ESP32-C2 has 40MHz, ESP32-H2 has 48MHz and ESP32-C5, C6, C61 and P4 has 80MHz
 // Note: ESP32-C6, C61, ESP32-P4 and ESP32-C5 have LP UART that will use only RTC_FAST or XTAL/2 as Clock Source
 bool HardwareSerial::setClockSource(SerialClkSrc clkSrc) {
-  return uartSetClockSource(_uart, (uart_sclk_t) clkSrc);
+  if (_uart) {
+    log_e("No Clock Source change was done. This function must be called before beginning UART%d.", _uart_nr);
+    return false;
+  }
+  return uartSetClockSource(_uart_nr, (uart_sclk_t) clkSrc);
 }
-
 // minimum total RX Buffer size is the UART FIFO space (128 bytes for most SoC) + 1. IDF imposition.
 // LP UART has FIFO of 16 bytes
 size_t HardwareSerial::setRxBufferSize(size_t new_size) {