[AArch64] Slight naming changes and comments for AArch64NamedImmMapper

Reviewers: echristo

Subscribers: llvm-commits

Follow-up to: http://reviews.llvm.org/D8496#158595

Relates to: http://reviews.llvm.org/rL235089


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237354 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed