[DAGCombiner] Use getTokenFactor in a few more cases.

SDNodes can only have 64k operands and for some inputs (e.g. large
number of stores), we can reach this limit when creating TokenFactor
nodes. This patch is a follow up to D56740 and updates a few more places
that potentially can create TokenFactors with too many operands.

Reviewers: efriedma, craig.topper, aemerson, RKSimon

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D59156

llvm-svn: 356668