dts: xtensa: espressif: esp32: add GPIO map for accessing full GPIO range

Add a GPIO pass-thru map for accessing the full range (0 to 39) of ESP32
GPIO pins by their datasheet number.

GPIOs 0 to 31 are mapped to gpio0 while GPIOs 32 to 39 are mapped to
gpio1.

Signed-off-by: Henrik Brix Andersen <henrik@brixandersen.dk>