[DAGCombiner] Remove mostly redundant calls to AddToWorklist

[DAGCombiner] Remove mostly redundant calls to AddToWorklist

Summary:
These calls change the order in which some nodes are processed and so have an effect on codegen.

The change in fixup-bw-copy.ll is due to (and (load anyext)) gets transformed into (load zext) while previously the and was removed by SimplifyDemandedBits, so the (load anyext) remained.

Reviewers: craig.topper, efriedma, RKSimon, lebedev.ri

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66543

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@369561 91177308-0d34-0410-b5e6-96231b3b80d8