Merging r260651:

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r260651 | Matthew.Arsenault | 2016-02-11 18:40:47 -0800 (Thu, 11 Feb 2016) | 7 lines

AMDGPU: Set element_size in private resource descriptor

Introduce a subtarget feature for this, and leave the default with
the current behavior which assumes up to 16-byte loads/stores can
be used. The field also seems to have the ability to be set to 2 bytes,
but I'm not sure what that would be used for.

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llvm-svn: 271679