perform conditional setup of the adc

this should be pretty uncontroversial  - instead of always initializing the ADC it will only happen the first time analogRead gets called. This prevents surprises when runnin bare-HAL code

Author: oclyke

cores/arduino/ard_sup/analog/ap3_analog.cpp

@@ -125,6 +125,12 @@ uint8_t _servoWriteBits = 8;  // 8-bit by default for writes
 
 uint16_t analogRead(uint8_t pinNumber)
 {
+    static bool ap3_adc_initialized = false;
+    if(!ap3_adc_initialized){
+        ap3_adc_setup();
+        ap3_adc_initialized = true;
+    }
+
     uint32_t ui32IntMask;
     am_hal_adc_sample_t Sample;
     uint32_t ui32NumSamples = 1;

cores/arduino/ard_sup/main.cpp

@@ -21,7 +21,7 @@ extern "C" int main(void)
 
   ap3_variant_init();
 
-  ap3_adc_setup();
+  // ap3_adc_setup();
 
   setup();
   for (;;)