2nd attempt at "fixing" amdgpu tests after r321575​

The test needs to be changed; it was exercising UB and that likely wasn't the intent of the test author.  I simply removed the checks because I have absolutely no idea what this test was trying to accomplish.  With multiple check patterns, no explanation, and no familiarity on my part with the ISA a true fix is going to have to come from someone familiar with the target.  

llvm-svn: 321591