DADCombiner: Don't simplify the token factor if the node's number of operands already...

DADCombiner: Don't simplify the token factor if the node's number of operands already exceeds TokenFactorInlineLimit

Summary:
  In parallelizeChainedStores, a TokenFactor was created with the size greater than 3000.
We found that DAGCombiner::visitTokenFactor will consume a huge amount of time on
such nodes. Since the number of operands already exceeds TokenFactorInlineLimit, we propose
to give up simplification with the consideration of compile time.

Reviewers:
  @spatel, @arsenm

Differential Revision:
  https://reviews.llvm.org/D84204