[AArch64][Falkor] Avoid HW prefetcher tag collisions (step 2)

Summary:
Avoid HW prefetcher instruction tag collisions in loops by inserting
MOVs to change the base address register of strided loads.

Reviewers: t.p.northover, mcrosier

Subscribers: aemerson, rengolin, javed.absar, kristof.beyls, hfinkel, llvm-commits

Differential Revision: https://reviews.llvm.org/D35366

llvm-svn: 308324