systemc: keep SC_CONCAT* macro

Call of TLM_DECLARE_EXTENDED_PHASE requires SC_CONCAT* macros.  This change
keeps those macros to avoid compile errors.

Change-Id: I573c4c126a350ef1a752d1c50658e7d9cedaaeae
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/24123
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/src/systemc/ext/tlm_core/2/generic_payload/phase.hh b/src/systemc/ext/tlm_core/2/generic_payload/phase.hh
index db5866a..df61ffa 100644
--- a/src/systemc/ext/tlm_core/2/generic_payload/phase.hh
+++ b/src/systemc/ext/tlm_core/2/generic_payload/phase.hh
@@ -106,12 +106,4 @@
 
 } // namespace tlm
 
-#undef SC_CONCAT_HELPER_
-#undef SC_CONCAT_HELPER_DEFERRED_
-#undef SC_CONCAT_HELPER_MORE_DEFERRED_
-
-#undef SC_STRINGIFY_HELPER_
-#undef SC_STRINGIFY_HELPER_DEFERRED_
-#undef SC_STRINGIFY_HELPER_MORE_DEFERRED_
-
 #endif /* __SYSTEMC_EXT_TLM_CORE_2_GENERIC_PAYLOAD_PHASE_HH__ */