[SYCL] Remove unfinished extension macro from sycl_khr_group_interface (#19911)

This extension will be merged into SYCL-Docs soon so this change removes
the `__DPCPP_ENABLE_UNFINISHED_KHR_EXTENSIONS` macro guard.

Signed-off-by: Michael Aziz <[email protected]>

Author: 0x12CC

sycl/include/sycl/khr/group_interface.hpp

@@ -11,9 +11,7 @@
 #include <sycl/id.hpp>
 #include <sycl/range.hpp>
 
-#ifdef __DPCPP_ENABLE_UNFINISHED_KHR_EXTENSIONS
 #define SYCL_KHR_GROUP_INTERFACE 1
-#endif
 
 #if __cplusplus >= 202302L && defined(__has_include)
 #if __has_include(<mdspan>)
@@ -23,7 +21,6 @@
 
 namespace sycl {
 inline namespace _V1 {
-#ifdef __DPCPP_ENABLE_UNFINISHED_KHR_EXTENSIONS
 namespace khr {
 
 // Forward declarations for traits.
@@ -265,6 +262,5 @@ template <typename Group> bool leader_of(Group g) {
 }
 
 } // namespace khr
-#endif
 } // namespace _V1
 } // namespace sycl