[clang] [NVPTX] Enable OpenCL 3d_image_writes support (PR #143331)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> LGTM but I'm never sure who owns this aspect of NVPTX. @Artem-B, @jhuber6 ?

I work at AMD and don't really know much about OpenCL.

https://github.com/llvm/llvm-project/pull/143331