rp2/boards/ARDUINO_NANO_RP2040_CONNECT: Add more external pins.

Add the missing A4, A5 external (Nina-W controlled) pins.

ports/rp2/boards/ARDUINO_NANO_RP2040_CONNECT/mpconfigboard.h

@@ -14,7 +14,7 @@
 #define MICROPY_USE_INTERNAL_ERRNO      (0)
 
 // Enable externally controlled pins.
-#define MICROPY_HW_PIN_EXT_COUNT        (5)
+#define MICROPY_HW_PIN_EXT_COUNT        (7)
 
 // Enable USB Mass Storage with FatFS filesystem.
 #define MICROPY_HW_USB_MSC              (1)

ports/rp2/boards/ARDUINO_NANO_RP2040_CONNECT/pins.csv

@@ -17,10 +17,12 @@ A0,GPIO26
 A1,GPIO27
 A2,GPIO28
 A3,GPIO29
-A4,GPIO12
-A5,GPIO13
+SDA,GPIO12
+SCL,GPIO13
 LEDR,EXT_GPIO0
 LEDG,EXT_GPIO1
 LEDB,EXT_GPIO2
-A6,EXT_GPIO3
-A7,EXT_GPIO4
+D18,EXT_GPIO3
+D19,EXT_GPIO4
+D20,EXT_GPIO5
+D21,EXT_GPIO6