[SYCL] Partially revert intel#185

Changes to tests are preserved

Signed-off-by: Alexey Sachkov <[email protected]>

Author: AlexeySachkov

sycl/include/CL/sycl/detail/kernel_desc.hpp

@@ -15,22 +15,10 @@ __SYCL_INLINE namespace cl {
 namespace sycl {
 namespace detail {
 
-namespace half_impl {
-
-class half;
-// Half type is defined as _Float16 on device and as manually implemented half
-// type on host. Integration header is generated by device compiler so it sees
-// half type as _Float16 and it will add _Float16 to integration header if it
-// is used in kernel name template parameters. To avoid errors in host
-// compilation we remove _Float16 from integration header using following macro.
-// Same thing goes about bool type which is defined as _Bool.
 #ifndef __SYCL_DEVICE_ONLY__
-#define _Float16 cl::sycl::detail::half_impl::half
 #define _Bool bool
 #endif
 
-} // namespace half_impl
-
 // kernel parameter kinds
 enum class kernel_param_kind_t {
   kind_accessor,