flash/nor/rp2040: fix building with MinGW toolchain

[donlon]

Hi, this patch fixes the errors when building with MinGW toolchain (x86_64-w64-mingw32)

../src/flash/nor/rp2040.c: In function 'rp2040_lookup_rom_symbol':
../src/flash/nor/rp2040.c:192:15: error: unknown type name 'uint'; did you mean 'u_int'?
  192 |         const uint offset_magic_to_table_ptr = flags == RT_FLAG_DATA ? 6 : 4;
      |               ^~~~
      |               u_int
...