[clang] Revert "[OpenCL] Set KHR extensions minimum version to OpenCL 1.0" (PR #175993)

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b-sumner wrote:

The situation here is that we have OpenCL C 2.0 device code calling get_image_width and get_image_height for all valid qualifications (read_only, read_write, etc.) on image_2d_depth_t and image2d_array_depth_t images and are seeing the no matching function complaint.  This is a regression.

https://github.com/llvm/llvm-project/pull/175993