- Implement all the I64Atomic operations on ARM
 - Change assembler methods to use Registers instead of memory operands
 - Move atomics64 test up be tested on all archs, disable tests on MIPS

BUG:v8:6532

Change-Id: I91bd42fa819f194be15c719266c36230f9c65db8
Reviewed-on: https://chromium-review.googlesource.com/1180211
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Reviewed-by: Ben Smith <binji@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55416}