Update esp32-hal-gpio.h

Author: Jason2866

Diff for: cores/esp32/esp32-hal-gpio.h

@@ -49,6 +49,13 @@ extern "C" {
 #define INPUT_PULLDOWN    0x09
 #define OPEN_DRAIN        0x10
 #define OUTPUT_OPEN_DRAIN 0x12
+#define SPECIAL           0xF0
+#define FUNCTION_1        0x00
+#define FUNCTION_2        0x20
+#define FUNCTION_3        0x40
+#define FUNCTION_4        0x60
+#define FUNCTION_5        0x80
+#define FUNCTION_6        0xA0
 #define ANALOG            0xC0
 
 //Interrupt Modes