Remove PIO global headers from UART object

Author: earlephilhower

cores/rp2040/SerialUART.cpp

@@ -19,6 +19,7 @@
  */
 
 #include "SerialUART.h"
+#include <hardware/uart.h>
 #include <hardware/gpio.h>
 
 bool SerialUART::setPinout(pin_size_t tx, pin_size_t rx) {

cores/rp2040/SerialUART.h

@@ -23,9 +23,10 @@
 
 #include <Arduino.h>
 #include "api/HardwareSerial.h"
-#include <hardware/uart.h>
 #include <stdarg.h>
 
+extern "C" typedef struct uart_inst uart_inst_t;
+
 class SerialUART : public HardwareSerial {
 public:
     SerialUART(uart_inst_t *uart, pin_size_t tx, pin_size_t rx) { _uart = uart; _tx = tx; _rx = rx; }