sycl : fixed sycl CLAMP to actually support strided view (#31784)
Modify `ggml_sycl_op_clamp` to use the unary helper function
`ggml_sycl_detail::ggml_sycl_op_unary` to handle non-contigous or
strided views. The fix uses a pattern that matches other stride-safe
unary ops, and is a simpler execution path.
Deleted dead template `unary_op_clamp_kernel`, the flat `clamp` kernel
launcher from element_wise.cpp, and deleted (now) unused
`SYCL_CLAMP_BLOCK_SIZE` from presets.hpp.