Core: fix NSPM default client ID assignment

If TFM_NS_CLIENT_IDENTIFICATION build option is disabled,
always use default NS client id of -1

Change-Id: I565bafd7eac9c30ec4e027ff9925ca483a875d9f
Signed-off-by: Miklos Balint <miklos.balint@arm.com>
diff --git a/interface/include/tfm_ns_svc.h b/interface/include/tfm_ns_svc.h
index 794cc5c..0399af9 100644
--- a/interface/include/tfm_ns_svc.h
+++ b/interface/include/tfm_ns_svc.h
@@ -48,7 +48,9 @@
 #define X(SVC_ENUM, SVC_HANDLER) SVC_ENUM,
 
     /* SVC API for Services */
+#ifdef TFM_NS_CLIENT_IDENTIFICATION
     LIST_SVC_NSPM
+#endif
 
 #undef X