Remove discussions of MBEDTLS_USE_PSA_CRYPTO in documentation

[gilles-peskine-arm]

Remove discussions of MBEDTLS_USE_PSA_CRYPTO in documentation. The documentation should now only what was formerly the behavior when MBEDTLS_USE_PSA_CRYPTO is enabled.

Note that while docs/use-psa-crypto.md will be partly obsolete (e.g. “why enable” is no longer relevant), some of the information is still relevant (at least limitations).

Follow-up to #9630

[gilles-peskine-arm]

I'm upping the size estimate. This is easy, but tedious: each place where MBEDTLS_USE_PSA_CRYPTO is mentioned is easy or trivial to update, but there are a lot of them.

[yanesca]

Manually inspected the files coming up in

grep -rIn -i 'USE[-_]PSA' . | sed 's/\([a-zA-Z0-9/_.]*:\).*/\1/' | uniq

and arrived at the following categorisation:

No Changes

./ChangeLog.d/
./tests/ - Tracked in #9726, code or better done as part of #9631
./tf-psa-crypto/tests/ - Code or better done as part of #9631
./tf-psa-crypto/drivers/builtin/src - Code or better done as part of #9631
./programs/ - Code or better done as part of #9631
./library/ - Code or better done as part of #9631
./framework/scripts/ - Code or better done as part of #9631

API documentation

PR: #9781

./tf-psa-crypto/drivers/builtin/include
./include/
./configs/

Standalone documentation

PR: #9818

./docs/
./README.md:

[yanesca]

Both PRs implementing this change have been merged.