[llvm] [AMDGPU] Avoid setting GLC for image atomics when result is unused (PR #150742)

[Jay Foad via llvm-commits]

jayfoad wrote:

> I'm working on implementing no-return type image atomic intrinsics and instructions.

We don't need new intrinsics, only new MachineInstrs.

> I'm happy to work on adding proper no-return variants, this is my first time writing tablegen. :-)

@sstipanovic has done a lot of work in `MIMGInstructions.td` recently and might be able to help if you need some help.

https://github.com/llvm/llvm-project/pull/150742