cpu: Eliminate the unused hasBranchTarget method in StaticInst.

This was once used to implement GDB single stepping back when it was
reimplemented for each ISA, but has not been used since 2014 when that
code was refactored.

Change-Id: If37ccfec2c43a33320d753c68892aa6fefd16b4f
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/51531
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: ZHENGRONG WANG <seanyukigeek@gmail.com>

src/cpu/static_inst.cc

@@ -33,23 +33,6 @@
 namespace gem5
 {
 
-bool
-StaticInst::hasBranchTarget(const TheISA::PCState &pc, ThreadContext *tc,
-                            TheISA::PCState &tgt) const
-{
-    if (isDirectCtrl()) {
-        tgt = branchTarget(pc);
-        return true;
-    }
-
-    if (isIndirectCtrl()) {
-        tgt = branchTarget(tc);
-        return true;
-    }
-
-    return false;
-}
-
 StaticInstPtr
 StaticInst::fetchMicroop(MicroPC upc) const
 {