psa: Accelerator support for Silabs SiWx91x devices

Enable acceleration for Silicon Labs SiWx91x devices.

Implementation is ported from Simplicity SDK 2024.12.0 and
applied to the Zephyr fork of mbed TLS.

Signed-off-by: Aksel Skauge Mellbye <aksel.mellbye@silabs.com>

Author: asmellby