[NFC] XFAIL entry_point_func.ll as call to spir_kernel is not allowed

Author: jsji

llvm-spirv/test/entry_point_func.ll

@@ -5,6 +5,9 @@
 ; RUN: llvm-spirv %t.bc -o %t.spv
 ; RUN: spirv-val %t.spv
 
+; TODO: adjust the test or revert XFAIL
+; XFAIL: *
+
 target datalayout = "e-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-n8:16:32:64"
 target triple = "spir64-unknown-unknown"