Build: Support building IPC model without tests

Refactors the build configuration variables so that the Core IPC tests
are only built if either CORE_TEST or REGRESSION is enabled (as well as
CORE_IPC). This matches the build behaviour for library model.

Adds a TFM_PARTITION_TEST_CORE_IPC build variable to make it possible
to compile-out the Core IPC test partition when the Core IPC tests are
not built.

Removes some unneeded build system behaviour that was conditional on
CORE_TEST to avoid causing problems when CORE_IPC is enabled.

Change-Id: Ia88bd3785817cc2dcedf88b737690fc32cc3266e
Signed-off-by: Jamie Fox <jamie.fox@arm.com>
diff --git a/interface/include/tfm_veneers.h b/interface/include/tfm_veneers.h
index ae4bb69..db3de27 100644
--- a/interface/include/tfm_veneers.h
+++ b/interface/include/tfm_veneers.h
@@ -107,13 +107,13 @@
 psa_status_t tfm_tfm_secure_client_service_sfn_run_tests_veneer(psa_invec *in_vec, size_t in_len, psa_outvec *out_vec, size_t out_len);
 #endif /* TFM_PARTITION_TEST_SECURE_SERVICES */
 
-#ifdef TFM_PSA_API
+#ifdef TFM_PARTITION_TEST_CORE_IPC
 /******** TFM_SP_IPC_SERVICE_TEST ********/
-#endif /* TFM_PSA_API */
+#endif /* TFM_PARTITION_TEST_CORE_IPC */
 
-#ifdef TFM_PSA_API
+#ifdef TFM_PARTITION_TEST_CORE_IPC
 /******** TFM_SP_IPC_CLIENT_TEST ********/
-#endif /* TFM_PSA_API */
+#endif /* TFM_PARTITION_TEST_CORE_IPC */
 
 #ifdef __cplusplus
 }