cpu: Eliminate the ThreadContext::microPC method.

This was originally intended to make it more efficient to get the
microPC without making a copy of the entire PCState object to return.
Now that the PCState is returned through a pointer without a copy and
the microPC can be accessed with an inline accessor, we don't need to
create a special accessor for it.

Change-Id: I1d354dfca6be5d954e147f23dc9d27917b379bf2
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52061
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Gabe Black <gabe.black@gmail.com>

src/cpu/o3/commit.hh

@@ -314,9 +314,6 @@ class Commit
     /** Returns the PC of a specific thread. */
     Addr instAddr(ThreadID tid) { return pc[tid]->instAddr(); }
 
-    /** Reads the micro PC of a specific thread. */
-    Addr microPC(ThreadID tid) { return pc[tid]->microPC(); }
-
   private:
     /** Time buffer interface. */
     TimeBuffer<TimeStruct> *timeBuffer;