rp2/rp2_flash: Support flash writes from PSRAM.

Add a 256 byte (FLASH_PAGE_SIZE) SRAM copy buffer to allow copies from
PSRAM to flash.  This would otherwise hardfault since PSRAM is disabled
when doing a write to flash.

Changes are:
- ports/rp2/rp2_flash.c: Add 256 byte (flash page size) SRAM copy buffer
                         for PSRAM to flash copies.
- ports/rp2/rp2_flash.c: Invalidate the XIP cache to purge any PSRAM
                         data before critical flash operations.

Co-authored-by: Phil Howard <github@gadgetoid.com>
Co-authored-by: Angus Gratton <angus@redyak.com.au>
Signed-off-by: Phil Howard <github@gadgetoid.com>

0 files changed, 0 insertions, 0 deletions