Finish adapting flash storage size

Before this, CIRCUITPY would start at 1MB anyway. This appeared to work
only because I hadn't checked the actual size of the CIRCUITPY drive,
and because until now the flash hadn't actually crossed that 1MB
boundary into CIRCUITPY storage.

WARNING: on pico_w, upgrading/downgrading CircuitPython across this commit
boundary will erase the CIRCUITPY filesystem. After this commit,
switching between pico and pico_w firmware will erase the CIRCUITPY
filesystem

ports/raspberrypi/boards/raspberry_pi_pico_w/mpconfigboard.mk

@@ -19,3 +19,5 @@ CIRCUITPY_SOCKETPOOL = 1
 CIRCUITPY_WIFI = 1
 
 CFLAGS += -DCYW43_PIN_WL_HOST_WAKE=24 -DCYW43_PIN_WL_REG_ON=23 -DCYW43_WL_GPIO_COUNT=3 -DCYW43_WL_GPIO_LED_PIN=0
+# Must be accompanied by a linker script change
+CFLAGS += -DRESERVED_FLASH='(1792 * 1024)'

ports/raspberrypi/supervisor/internal_flash.c

@@ -46,7 +46,13 @@
 #include "src/rp2_common/hardware_flash/include/hardware/flash.h"
 #include "src/common/pico_binary_info/include/pico/binary_info.h"
 
+#if !defined(RESERVED_FLASH)
 #define RESERVED_FLASH (1 * 1024 * 1024)
+#endif
+
+#if !defined(TOTAL_FLASH_MINIMUM)
+#define TOTAL_FLASH_MINIMUM (2 * 1024 * 1024)
+#endif
 
 // TODO: Split the caching out of supervisor/shared/external_flash so we can use it.
 #define SECTOR_SIZE 4096
@@ -60,7 +66,7 @@ void supervisor_flash_init(void) {
         BINARY_INFO_MAKE_TAG('C', 'P'),
         "CircuitPython",
         RESERVED_FLASH,
-        (1 * 1024 * 1024), // This is a minimum. We can't set it dynamically.
+        TOTAL_FLASH_MINIMUM - RESERVED_FLASH, // This is a minimum. We can't set it dynamically.
         NULL,
         BINARY_INFO_BLOCK_DEV_FLAG_READ |
         BINARY_INFO_BLOCK_DEV_FLAG_WRITE |