[SYCL][NFC] Drop legacy PlatformUtil (#20175)

This is a collection of utility functions needed to provide device info
for the host device which had been completely removed a while ago.

Author: AlexeySachkov

sycl/source/CMakeLists.txt

@@ -294,7 +294,6 @@ set(SYCL_COMMON_SOURCES
     "detail/queue_impl.cpp"
     "detail/os_util.cpp"
     "detail/persistent_device_code_cache.cpp"
-    "detail/platform_util.cpp"
     "detail/preview_marker.cpp"
     "detail/reduction.cpp"
     "detail/sampler_impl.cpp"

sycl/source/detail/platform_util.cpp

@@ -6,7 +6,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include <detail/platform_util.hpp>
 #include <sycl/__spirv/spirv_ops.hpp>
 #include <sycl/detail/iostream_proxy.hpp>
 #include <sycl/exception.hpp>