crypto: Allow for direct linking with nrf_oberon for TF-M builds

-This commit allows linking to nrf_oberon for samples/apps that
 enable TF-M but still rely on ocrypto_ prefixed APIs because some
 of the crypto not being available in PSA crypto APIs.

Note: Previous to this it was required to enable NORDIC_SECURITY_BACKEND
to get access to nrf_oberon library (and ocrypto_ prefixed APIs). This
commit will allow CONFIG_NRF_OBERON to be used as a signal that
ocrypto_ APIs are required with NRF_SECURITY being enabled

ref: NCSDK-29217

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

Author: frkv

subsys/nrf_security/src/CMakeLists.txt

@@ -203,7 +203,7 @@ endif()
 add_subdirectory(drivers)
 
 # Add legacy Mbed TLS APIs
-if(CONFIG_MBEDTLS_LEGACY_CRYPTO_C)
+if(CONFIG_MBEDTLS_LEGACY_CRYPTO_C OR (CONFIG_NRF_OBERON AND CONFIG_BUILD_WITH_TFM))
   add_subdirectory(legacy)
 endif()