rp2: Make FLASH LENGTH match PICO_FLASH_SIZE_BYTES in .ld files.

With a fallback to default sizes if `PICO_FLASH_SIZE_BYTES` is not defined.

Signed-off-by: Dryw Wade <dryw.wade@sparkfun.com>

ports/rp2/CMakeLists.txt

@@ -528,6 +528,20 @@ target_link_options(${MICROPY_TARGET} PRIVATE
     -Wl,--wrap=runtime_init_clocks
 )
 
+if(PICO_FLASH_SIZE_BYTES GREATER 0)
+    target_link_options(${MICROPY_TARGET} PRIVATE
+        -Wl,--defsym=__micropy_flash_size__=${PICO_FLASH_SIZE_BYTES}
+    )
+elseif(PICO_RP2040)
+    target_link_options(${MICROPY_TARGET} PRIVATE
+        -Wl,--defsym=__micropy_flash_size__=2048k # Default to 2MB
+    )
+elseif(PICO_RP2350)
+    target_link_options(${MICROPY_TARGET} PRIVATE
+        -Wl,--defsym=__micropy_flash_size__=4096k # Default to 4MB
+    )
+endif()
+
 if(PICO_RP2350)
     target_link_options(${MICROPY_TARGET} PRIVATE
         -Wl,--defsym=__micropy_extra_stack__=4096

ports/rp2/memmap_mp_rp2040.ld

@@ -23,7 +23,7 @@
 
 MEMORY
 {
-    FLASH(rx) : ORIGIN = 0x10000000, LENGTH = 2048k
+    FLASH(rx) : ORIGIN = 0x10000000, LENGTH = __micropy_flash_size__
     RAM(rwx) : ORIGIN =  0x20000000, LENGTH = 256k
     SCRATCH_X(rwx) : ORIGIN = 0x20040000, LENGTH = 4k
     SCRATCH_Y(rwx) : ORIGIN = 0x20041000, LENGTH = 4k

ports/rp2/memmap_mp_rp2350.ld

@@ -23,7 +23,7 @@
 
 MEMORY
 {
-    FLASH(rx) : ORIGIN = 0x10000000, LENGTH = 4096k
+    FLASH(rx) : ORIGIN = 0x10000000, LENGTH = __micropy_flash_size__
     RAM(rwx) : ORIGIN =  0x20000000, LENGTH = 512k
     SCRATCH_X(rwx) : ORIGIN = 0x20080000, LENGTH = 4k
     SCRATCH_Y(rwx) : ORIGIN = 0x20081000, LENGTH = 4k