doc: crypto: Correct thread-safety for PSA crypto APIs

-Mbed TLS 3.6.0 adds thread safety for PSA crypto APIs, but this has
 not been reflected in the documentation. Removed a caution related
 to this.

Signed-off-by: Frank Audun Kvamtrø <[email protected]>

Author: frkv

doc/nrf/libraries/security/nrf_security/doc/configuration.rst

@@ -19,9 +19,6 @@ PSA crypto support is included by default when you enable nRF Security through t
 PSA crypto support is provided through PSA Crypto APIs and is implemented by PSA core.
 PSA core uses PSA drivers to implement the cryptographic features either in software, or using hardware accelerators.
 
-.. caution::
-   The PSA Crypto APIs are only thread safe when provided by TF-M.
-
 .. _legacy_crypto_support:
 
 Legacy crypto support