Revert "[SCCP] Use SimplifyBinOp for non-integer constant/expressions & overdef."

This reverts commit 1a02aaea. Crashes on
the following test case:

$ cat crash.ll
source_filename = "__compute_module"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-grtev4-linux-gnu"

@0 = private unnamed_addr constant [24 x i8] c"\00\00\C0\7F\00\00\C0\7F\09\85\08?\ED\C94\FE~\EB/\F3\90\CF\BA\C1"
@1 = private unnamed_addr constant [24 x i8] c"\00\00\C0\7F\A3\A0\0FA\00\00\C0\7F\00\00\C0\7F\00\00\00\00\02\9AA\00"

define void @IgammaSpecialValues.448() {
entry:
  br label %fusion.26.loop_header.dim.0

fusion.26.loop_header.dim.0:                      ; preds = %fusion.26.loop_header.dim.0, %entry
  %fusion.26.invar_address.dim.0.0 = phi i64 [ 0, %entry ], [ %invar.inc17, %fusion.26.loop_header.dim.0 ]
  %0 = getelementptr inbounds [6 x float], [6 x float]* bitcast ([24 x i8]* @0 to [6 x float]*), i64 0, i64 %fusion.26.invar_address.dim.0.0
  %1 = load float, float* %0
  %2 = fmul float %1, 0.000000e+00
  %3 = getelementptr inbounds [6 x float], [6 x float]* bitcast ([24 x i8]* @1 to [6 x float]*), i64 0, i64 %fusion.26.invar_address.dim.0.0
  %4 = load float, float* %3
  %5 = fneg float %4
  %6 = fadd float %2, %5
  %invar.inc17 = add nuw nsw i64 %fusion.26.invar_address.dim.0.0, 1
  br label %fusion.26.loop_header.dim.0
}

$ opt -ipsccp -S < crash.ll
opt: llvm/include/llvm/Analysis/ValueLattice.h:251: bool llvm::ValueLatticeElement::markConstant(llvm::Constant *, bool): Assertion `getConstant() == V && "Marking constant with different value"' failed.