[Upstream] Fix errors about unsupported sampler/image type

clang emits errors from SYCL headers about unsupported OpenCL types:
```
lib/clang/10.0.0/include/CL/__spirv/spirv_ops.hpp:24:49: error: unknown type name '__ocl_sampler_t'
extern SampledType __spirv_SampledImage(ImageT, __ocl_sampler_t)
```

We reused OpenCL types for SYCL, like here https://reviews.llvm.org/D63710 .
But we can also try another approaches.