samples: crypto: aes_gcm: fix Oberon test scenario for nRF54L15

Disabling the CRACEN driver altogether makes the key generation fail.
Only disable the CRACEN AEAD driver instead.

Signed-off-by: Tomi Fontanilles <[email protected]>

Author: tomi-font

samples/crypto/aes_gcm/sample.yaml

@@ -27,7 +27,7 @@ tests:
     sysbuild: true
     extra_args:
       - CONFIG_PSA_CRYPTO_DRIVER_OBERON=y
-      - CONFIG_PSA_CRYPTO_DRIVER_CRACEN=n
+      - CONFIG_PSA_USE_CRACEN_AEAD_DRIVER=n
     tags:
       - introduction
       - psa