feat(linux): crypto: Add TRNG and tcrypt documentation for DTHEv2

[Pratham-T]

The support for OPTEE TRNG has been enabled in AM62L. As well as our perf tests are now updated to cover AM62L as well. This PR adds documentation covering the TRNG usage and also adds tcrypt test numbers. The content is same as SA2UL_OMAP documentation with only the performance numbers changed.

[Copilot]

Pull request overview

This PR adds comprehensive documentation for TRNG (True Random Number Generator) and tcrypt testing capabilities for the DTHEv2 crypto driver on AM62L platforms. The content is adapted from SA2UL_OMAP documentation with platform-specific performance numbers.

Key Changes:

• Added TRNG hardware accelerator usage documentation including driver verification, device access, and testing procedures
• Added tcrypt module performance testing examples with detailed benchmark results for AES encryption/decryption

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[github-actions]

New warnings found with rstcheck:

source/linux/Foundational_Components/Kernel/Kernel_Drivers/Crypto/DTHEv2.rst:286: (WARNING/2) Title underline too short.

[Pratham-T]

Addressed all the review comments.
Also reviewed the Vale warnings and corrected most of them. The remaining ones are not very relevant or not possible to correct.

Also, both these sections' contents were directly lifted from SA2UL documentation. Shouldn't all these changes be made there as well?

[StaticRocket]

Good point @Pratham-T , this should probably be moved into a file to be included by both, or a common file to be included by the toc tree of both devices. Either is more useful than direct copy/paste right now considering the tooling didn't change at all between devices.

[Pratham-T]

Good point @Pratham-T , this should probably be moved into a file to be included by both, or a common file to be included by the toc tree of both devices. Either is more useful than direct copy/paste right now considering the tooling didn't change at all between devices.

Actually, I am thinking to merge both the files by next SDK release. The feature parity is now close to zero, most of the tests made for OMAP/SA2UL devices now also cover DTHEv2. And by next release, this will be all the tests (hopefully).

The split was made because in the initial DTHEv2 release, there were a lot of differences, causing a lot of messy ifconfig blocks if kept in the same file. But by next release, I think the only thing different in DTHEv2 will be the performance numbers in the tests (apart from some small configs here and there of course). I think the better course of action seeing the near future here is moving the code-blocks having the test and performance numbers to different files for different crypto engines and include in the main crypto file under respective ifconfig.

[StaticRocket]

Alright, with that in mind I think it's fine to take this as is, considering a larger cleanup is pending.

Feedback addressed.