[DAG] Fix Big Endian in Load-Store forwarding

Summary:
Correct offset calculation in load-store forwarding for big-endian
targets.

Reviewers: rnk, RKSimon, waltl

Subscribers: sdardis, nemanjai, hiraditya, jrtc27, atanasyan, jsji, llvm-commits

Differential Revision: https://reviews.llvm.org/D53147

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@344272 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed