[SYCL] Remove old extension header (#494)

* Remove old extension header

Signed-off-by: mdimakov <[email protected]>

* Clang-format fix

Author: maximdimakov

SYCL/ESIMD/api/slm_gather_scatter_rgba.cpp

@@ -9,8 +9,8 @@
 #include "../esimd_test_utils.hpp"
 
 #include <CL/sycl.hpp>
-#include <CL/sycl/INTEL/esimd.hpp>
 #include <iostream>
+#include <sycl/ext/intel/experimental/esimd.hpp>
 
 using namespace cl::sycl;