Revert "[FastISel][AArch64] Add custom lowering for GEPs."

This breaks our internal build bots. Reverting it to get the bots green again.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219776 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Remove outdated comment

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219777 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Use existing variable

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219778 91177308-0d34-0410-b5e6-96231b3b80d8