[AArch64] Scale offsets by the size of the memory operation. NFC.

The immediate in the load/store should be scaled by the size of the memory
operation, not the size of the register being loaded/stored.  This change gets
us one step closer to forming LDPSW instructions.  This change also enables
pre- and post-indexing for halfword and byte loads and stores.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@248804 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed