systemc: Get rid of an unused private member in sc_clock.

It's not useful, and having it makes clang upset.

Change-Id: I51366fd18a287e186c88f08af5c6ba8692779003
Reviewed-on: https://gem5-review.googlesource.com/c/13876
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
diff --git a/src/systemc/channel/sc_clock.cc b/src/systemc/channel/sc_clock.cc
index 7ab86ee..86a279b 100644
--- a/src/systemc/channel/sc_clock.cc
+++ b/src/systemc/channel/sc_clock.cc
@@ -47,7 +47,6 @@
 class ClockTick : public ScEvent
 {
   private:
-    ::sc_core::sc_clock *clock;
     ::sc_core::sc_time _period;
     std::string name;
     Process *p;
@@ -57,7 +56,7 @@
     ClockTick(::sc_core::sc_clock *clock, bool to,
             ::sc_core::sc_time _period) :
         ScEvent([this]() { tick(); }),
-        clock(clock), _period(_period), name(clock->basename()), p(nullptr),
+        _period(_period), name(clock->basename()), p(nullptr),
         funcWrapper(clock, to ? &::sc_core::sc_clock::tickUp :
                                 &::sc_core::sc_clock::tickDown)
     {