[ARM][AArch64] Turn on by default interleaved access lowering

Summary:
Interleaved access lowering removes a memory operation and a
sequence of vector shuffles and replaces it with a series of
memory operations. This should be always beneficial.

This pass in only enabled on ARM/AArch64.

Reviewers: rengolin

Subscribers: aemerson, llvm-commits, rengolin

Differential Revision: http://reviews.llvm.org/D12145

llvm-svn: 246540