[SYCL][E2E] Mark bfloat16 AOT test unsupported (#17589)

It fails in precommit L0 Gen12 but passes in postcommit L0 Gen12, weird.

---------

Signed-off-by: Sarnie, Nick <[email protected]>

Author: sarnex

sycl/test-e2e/BFloat16/bfloat16_example_aot_gpu.cpp

@@ -5,8 +5,8 @@
 
 // REQUIRES: opencl-aot, ocloc, gpu-intel-gen12, any-device-is-gpu
 
-// XFAIL: linux
-// XFAIL-TRACKER: https://github.com/intel/llvm/issues/17305
+// UNSUPPORTED: true
+// UNSUPPORTED-TRACKER: https://github.com/intel/llvm/issues/17305
 
 // RUN: %clangxx -fsycl -fsycl-targets=spir64_gen -Xsycl-target-backend "-device gen12lp" %s -o %t.out
 // RUN: %if gpu %{%{run} %t.out %}