[arduino] 优化默认代码

bsp/stm32/stm32f469-st-disco/applications/arduino_main.cpp

@@ -10,17 +10,15 @@
 
 #include <Arduino.h>
 
-uint8_t led = LED_BUILTIN;
-
 void setup(void)
 {
     /* put your setup code here, to run once: */
-    pinMode(led, OUTPUT);
+    pinMode(LED_BUILTIN, OUTPUT);
 }
 
 void loop(void)
 {
     /* put your main code here, to run repeatedly: */
-    digitalWrite(led, !digitalRead(led));
+    digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
     delay(100);
 }

bsp/stm32/stm32l475-atk-pandora/applications/arduino_main.cpp

@@ -10,17 +10,15 @@
 
 #include <Arduino.h>
 
-uint8_t led = LED_BUILTIN;
-
 void setup(void)
 {
     /* put your setup code here, to run once: */
-    pinMode(led, OUTPUT);
+    pinMode(LED_BUILTIN, OUTPUT);
 }
 
 void loop(void)
 {
     /* put your main code here, to run repeatedly: */
-    digitalWrite(led, !digitalRead(led));
+    digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
     delay(100);
 }