cfg: check for led and button GPIO settings (#2177)

In case board configuration is empty, loop should try to check at least once

code/espurna/button.ino

@@ -568,7 +568,7 @@ void buttonSetup() {
 
         _buttons.reserve(buttons);
 
-        for (unsigned char index = 0; index < buttons; ++index) {
+        for (unsigned char index = 0; index < ButtonsMax; ++index) {
             const auto pin = getSetting({"btnGPIO", index}, _buttonPin(index));
             if (!gpioValid(pin)) {
                 break;

code/espurna/led.ino

@@ -336,7 +336,7 @@ void ledSetup() {
 
     _leds.reserve(leds);
 
-    for (unsigned char index=0; index < leds; ++index) {
+    for (unsigned char index=0; index < LedsMax; ++index) {
         const auto pin = getSetting({"ledGPIO", index}, _ledPin(index));
         if (!gpioValid(pin)) {
             break;