SHA: fix tracking buffered bytes

[bugadani]

Fixes #4718

process_update only handles data in block sized chunks. After processing a message, it copies back the "remaining" data into the item's buffer. Previously, the function failed to update the number of buffered bytes in the buffer, essentially losing parts of the message. This PR fixes this issue.

[Copilot]

Pull request overview

This PR fixes a critical bug in the SHA accelerator where hash calculations produced incorrect results for certain input sizes. The root cause was that the process_update function failed to update the buffered_bytes field after copying unprocessed bytes back to the buffer, causing parts of messages to be lost in subsequent operations.

• Fixed the missing buffered_bytes update in process_update function
• Refactored duplicate state restoration code into a dedicated restore_state function
• Enhanced test coverage to include non-block-aligned buffer sizes (264 bytes)

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
esp-hal/src/sha.rs	Fixed the critical buffered_bytes tracking bug in process_update, refactored state restoration into a helper function, and added debug logging
hil-test/src/bin/ecc_rsa_sha.rs	Enhanced test to include non-block-aligned size (264 bytes) to verify the fix works for partial blocks
esp-hal/CHANGELOG.md	Added entry documenting the SHA hash calculation fix

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[MabezDev]

Thanks!