[SYCL][HIP] Disable three failing tests

SYCL/DiscardEvents/discard_events_usm.cpp

@@ -1,6 +1,7 @@
 // FIXME unsupported on level_zero until L0 Plugin support becomes available for
 // discard_queue_events
-// UNSUPPORTED: level_zero
+// FIXME unsupported in HIP plugin
+// UNSUPPORTED: level_zero || hip
 //
 // RUN: %clangxx -fsycl -fsycl-targets=%sycl_triple %s -o %t.out
 //

SYCL/DiscardEvents/discard_events_usm_ooo_queue.cpp

@@ -1,3 +1,5 @@
+// FIXME: fails on HIP plugin
+// UNSUPPORTED: hip
 // RUN: %clangxx -fsycl -fsycl-targets=%sycl_triple %s -o %t.out
 //
 // RUN: env SYCL_PI_TRACE=2 %CPU_RUN_PLACEHOLDER %t.out &> %t.txt

SYCL/DiscardEvents/invalid_event.cpp

@@ -1,3 +1,5 @@
+// FIXME: fails on HIP
+// UNSUPPORTED: hip
 // RUN: %clangxx -fsycl -fsycl-targets=%sycl_triple %s -o %t.out
 //
 // RUN: %HOST_RUN_PLACEHOLDER %t.out