Consolidate the flash patches to fix build (#6850)

nuttx-patches/workarround_for_flash_data_cache_corruption.patch was
   patching a file patched in nuttx-patches/wip_inflight_to_upstream.patch

   The changes in workarround_for_flash_data_cache_corruption.patch
   will be submitted upstream once refactored (upstream coding style
   compliant and moved to correct location)