pico: set flash size to 4M for 2350 blits

This is as big as we can handle with the current translation setup

32blit-pico/memmap_blit_2350.ld.in

diff --git a/32blit-pico/memmap_blit_2350.ld.in b/32blit-pico/memmap_blit_2350.ld.in
index a180b05..98526ca 100644
--- a/32blit-pico/memmap_blit_2350.ld.in
+++ b/32blit-pico/memmap_blit_2350.ld.in
@@ -23,7 +23,7 @@
 
 MEMORY
 {
-    FLASH(rx) : ORIGIN = 0x10000000 + ${FLASH_OFFSET_BYTES}, LENGTH = 2048k
+    FLASH(rx) : ORIGIN = 0x10000000 + ${FLASH_OFFSET_BYTES}, LENGTH = 4096k
     RAM(rwx) : ORIGIN =  0x20008000, LENGTH = 480k
     /*SCRATCH_X(rwx) : ORIGIN = 0x20080000, LENGTH = 4k
     SCRATCH_Y(rwx) : ORIGIN = 0x20081000, LENGTH = 4k*/
@@ -286,4 +286,4 @@
     /* todo assert on extra code */
 
     __flash_binary_size = __flash_binary_end - __flash_binary_start;
-}
\ No newline at end of file
+}