ART-tests: Remove DX dependency from 660-checker-simd-sad-*

For these tests, DX and D8 generates identical code (modulo
register numbers). Still, in certain test cases, in the
"loop_optimization (before)" phase the order of two Phi instructions
is swapped.
This CL updates the CHECK conditions and enables D8.

Test: art/test.py -b -r --host -t 660-checker-simd-sad-*
Bug: 65168732

Change-Id: I48483d5acff72ca7b7b7c46f9bdd10322fd21d21
12 files changed