Support 128-bit flash programming units

[aidangarske]

Add configurable 8-byte and 16-byte flash programming units. Keeps the 8 byte as default. STM32H563 can only program internal flash in 128-bit quadwords this is needed wolfTrust integration

[Copilot]

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Pull request overview

Adds configurable 8-byte and 16-byte flash programming units, preserving 8-byte units by default and adapting NVM flash state handling and tests for 128-bit programming targets.

Changes:

• Documents and exposes WOLFHSM_CFG_FLASH_UNIT_SIZE with support for 8- and 16-byte units.
• Adds a 16-byte whFlashUnit representation and conversion helpers.
• Updates NVM flash state encoding and tests to use the configured unit size.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
wolfhsm/wh_settings.h	Documents the configurable flash unit size.
wolfhsm/wh_flash_unit.h	Defines 8-byte and 16-byte flash unit representations.
src/wh_nvm_flash.c	Adapts NVM state encoding and decoding to the configurable unit type.
test/wh_test_nvm_flash.c	Updates flash and NVM tests for variable unit sizes.
test/Makefile	Adds the FLASH_UNIT_SIZE build-time override.

Suppressed comments (1)

test/wh_test_nvm_flash.c:1

• This description is only correct for the default 8-byte unit size. With FLASH_UNIT_SIZE=16, this read has 14 leading bytes and 7 trailing bytes, with no aligned middle portion, so it does not exercise the claimed three-phase path. Derive the offset and length from WHFU_BYTES_PER_UNIT (or update the test comment and scenario) so the 16-byte configuration also validates an aligned middle read.

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