uartEnd: Unlock mutex before detaching rx and tx (espressif#554)

* uartEnd: Unlock mutex before detaching rx and tx

This should solve the device freezing issue when Serial.end() is called

* Unlock UART MUTEX only for detaching Rx and Tx

* Thanks to @me-no-dev for pointing it out that
   uart->dev->conf0.val can be inside mutex lock

Author: Raienryu97

cores/esp32/esp32-hal-uart.c

@@ -197,7 +197,7 @@ uart_t* uartBegin(uint8_t uart_nr, uint32_t baudrate, uint32_t config, int8_t rx
     uart->dev->conf0.val = config;
     #define TWO_STOP_BITS_CONF 0x3
     #define ONE_STOP_BITS_CONF 0x1
-	
+
     if ( uart->dev->conf0.stop_bit_num == TWO_STOP_BITS_CONF) {
         uart->dev->conf0.stop_bit_num = ONE_STOP_BITS_CONF;
         uart->dev->rs485_conf.dl1_en = 1;
@@ -228,11 +228,12 @@ void uartEnd(uart_t* uart)
         vQueueDelete(uart->queue);
     }
 
-    uartDetachRx(uart);
-    uartDetachTx(uart);
-
     uart->dev->conf0.val = 0;
+
     UART_MUTEX_UNLOCK();
+
+    uartDetachRx(uart);
+    uartDetachTx(uart);
 }
 
 uint32_t uartAvailable(uart_t* uart)
@@ -419,4 +420,3 @@ int log_printf(const char *format, ...)
     }
     return len;
 }
-