Update pins_arduino.h (espressif#2120)

Bugfix: pin A14 was double defined; pin A15 was missing.

Author: cyberman54

Diff for: variants/lopy4/pins_arduino.h

@@ -48,7 +48,7 @@ static const uint8_t A11 = 0;
 static const uint8_t A12 = 2;
 static const uint8_t A13 = 15;
 static const uint8_t A14 = 13;
-static const uint8_t A14 = 12;
+static const uint8_t A15 = 12;
 static const uint8_t A16 = 14;
 static const uint8_t A17 = 27;
 static const uint8_t A18 = 25;