systemc: Get rid of the unused Process::_procKind.

This seems to be a leftover from an earlier implementation.

Change-Id: I63d7e576fd3c11cf73769c34bbc97a4d3bbbdaeb
Reviewed-on: https://gem5-review.googlesource.com/c/13311
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/systemc/core/process.hh

@@ -160,7 +160,6 @@ class Process : public ::sc_core::sc_process_b, public ListNode
     InternalScEvent _terminatedEvent;
 
     ProcessFuncWrapper *func;
-    sc_core::sc_curr_proc_kind _procKind;
 
     bool _internal;