Add required code to psa_sim_generate.pl

Non generated code was unfortnuately added to psa_sim_crypto_server.c,
fix that by adding it to the generation scripts.

Signed-off-by: Paul Elliott <paul.elliott@arm.com>

tests/psa-client-server/psasim/src/psa_sim_generate.pl

@@ -302,6 +302,10 @@ sub server_implementations_header
 #if !defined(MBEDTLS_PSA_CRYPTO_C)
 #error "Error: MBEDTLS_PSA_CRYPTO_C must be enabled on server build"
 #endif
+
+#if defined(MBEDTLS_TEST_HOOKS)
+void (*mbedtls_test_hook_error_add)(int, int, const char *, int);
+#endif
 EOF
 }