Bring pins in line with board documentation.

This brings the pins in line with the documented [pinouts]. The only
"special" pins:

 - GP0, GP1 are mentioned as the default UART, so we init them as
   such and give them the TX and RX alternative names.
 - GP16 is connected to the onboard neopixel DIN line and we assign it
   the NEOPIXEL name. (Power of the neopixel is connected to the 3.3V
   rail, not a pin. See [schematic].)
 - GP26, GP27, GP28, GP29 have unambiguous ADC designations in the
   [pinouts], so we assign the `A` analogue names as the Pico board
   definition does.

  [pinouts]: https://www.waveshare.com/wiki/RP2040-Zero#Pinouts
  [schematic]: https://www.waveshare.com/w/upload/4/4c/RP2040_Zero.pdf

Author: Chris Wesseling

ports/raspberrypi/boards/waveshare_rp2040_zero/pins.c

@@ -5,11 +5,9 @@ STATIC const mp_rom_map_elem_t board_module_globals_table[] = {
 
     { MP_ROM_QSTR(MP_QSTR_GP0), MP_ROM_PTR(&pin_GPIO0) },
     { MP_ROM_QSTR(MP_QSTR_TX), MP_ROM_PTR(&pin_GPIO0) },
-    { MP_ROM_QSTR(MP_QSTR_D6), MP_ROM_PTR(&pin_GPIO0) },
 
     { MP_ROM_QSTR(MP_QSTR_GP1), MP_ROM_PTR(&pin_GPIO1) },
     { MP_ROM_QSTR(MP_QSTR_RX), MP_ROM_PTR(&pin_GPIO1) },
-    { MP_ROM_QSTR(MP_QSTR_D7), MP_ROM_PTR(&pin_GPIO1) },
 
     { MP_ROM_QSTR(MP_QSTR_GP2), MP_ROM_PTR(&pin_GPIO2) },
     { MP_ROM_QSTR(MP_QSTR_GP3), MP_ROM_PTR(&pin_GPIO3) },
@@ -25,21 +23,16 @@ STATIC const mp_rom_map_elem_t board_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_GP13), MP_ROM_PTR(&pin_GPIO13) },
     { MP_ROM_QSTR(MP_QSTR_GP14), MP_ROM_PTR(&pin_GPIO14) },
     { MP_ROM_QSTR(MP_QSTR_GP15), MP_ROM_PTR(&pin_GPIO15) },
-    /* { MP_ROM_QSTR(MP_QSTR_GP16), MP_ROM_PTR(&pin_GPIO16) }, */
+    { MP_ROM_QSTR(MP_QSTR_GP16), MP_ROM_PTR(&pin_GPIO16) },
     { MP_ROM_QSTR(MP_QSTR_NEOPIXEL), MP_ROM_PTR(&pin_GPIO16) },
     { MP_ROM_QSTR(MP_QSTR_GP17), MP_ROM_PTR(&pin_GPIO17) },
     { MP_ROM_QSTR(MP_QSTR_GP18), MP_ROM_PTR(&pin_GPIO18) },
     { MP_ROM_QSTR(MP_QSTR_GP19), MP_ROM_PTR(&pin_GPIO19) },
     { MP_ROM_QSTR(MP_QSTR_GP20), MP_ROM_PTR(&pin_GPIO20) },
     { MP_ROM_QSTR(MP_QSTR_GP21), MP_ROM_PTR(&pin_GPIO21) },
     { MP_ROM_QSTR(MP_QSTR_GP22), MP_ROM_PTR(&pin_GPIO22) },
-
-    { MP_ROM_QSTR(MP_QSTR_SMPS_MODE), MP_ROM_PTR(&pin_GPIO23) },
     { MP_ROM_QSTR(MP_QSTR_GP23), MP_ROM_PTR(&pin_GPIO23) },
-
-    { MP_ROM_QSTR(MP_QSTR_VBUS_SENSE), MP_ROM_PTR(&pin_GPIO24) },
     { MP_ROM_QSTR(MP_QSTR_GP24), MP_ROM_PTR(&pin_GPIO24) },
-
     { MP_ROM_QSTR(MP_QSTR_GP25), MP_ROM_PTR(&pin_GPIO25) },
 
     { MP_ROM_QSTR(MP_QSTR_GP26_A0), MP_ROM_PTR(&pin_GPIO26) },
@@ -54,8 +47,9 @@ STATIC const mp_rom_map_elem_t board_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR_GP28), MP_ROM_PTR(&pin_GPIO28) },
     { MP_ROM_QSTR(MP_QSTR_A2), MP_ROM_PTR(&pin_GPIO28) },
 
+    { MP_ROM_QSTR(MP_QSTR_GP29_A3), MP_ROM_PTR(&pin_GPIO29) },
+    { MP_ROM_QSTR(MP_QSTR_GP29), MP_ROM_PTR(&pin_GPIO29) },
     { MP_ROM_QSTR(MP_QSTR_A3), MP_ROM_PTR(&pin_GPIO29) },
-    { MP_ROM_QSTR(MP_QSTR_VOLTAGE_MONITOR), MP_ROM_PTR(&pin_GPIO29) },
 
     { MP_ROM_QSTR(MP_QSTR_UART), MP_ROM_PTR(&board_uart_obj) },
 };