Core: Enable platform specific extensions to the core set of SVC handlers

Support is provided for both the PSA IPC and Library models.

To enable platform specific SVC handlers, add
-DPLATFORM_SVC_HANDLERS=True to the CMAKE command line.

When PLATFORM_SVC_HANDLERS is defined, user must provide an
implementation of:

   int32_t platform_svc_handlers(tfm_svc_number_t svc_num,
                                 uint32_t *ctx, uint32_t lr);

Change-Id: I5fc641038732d2630e954f6c9b12df929b65c24a
Signed-off-by: Alan DeMars <ademars@ti.com>
diff --git a/CommonConfig.cmake b/CommonConfig.cmake
index 0c9c764..0e83118 100644
--- a/CommonConfig.cmake
+++ b/CommonConfig.cmake
@@ -155,6 +155,10 @@
 # Option to demonstrate usage of secure-only peripheral
 set (SECURE_UART1 OFF)
 
+if (PLATFORM_SVC_HANDLERS)
+	add_definitions(-DPLATFORM_SVC_HANDLERS)
+endif()
+
 if (REGRESSION)
 	set(SERVICES_TEST_ENABLED ON)
 endif()