Merging r275868:

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r275868 | arsenm | 2016-07-18 11:34:48 -0700 (Mon, 18 Jul 2016) | 4 lines

AMDGPU: Remove dead code and redundant check

Non intrinsic calls aren't really handled, and this
IntrinsicInst dyn_cast checks for the function for us.
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llvm-svn: 277076