[AMDGPU][NFC] Fix clang frontend<->sema layering issue

Author: rupprecht

clang/lib/Sema/SemaAMDGPU.cpp

@@ -11,9 +11,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "clang/Sema/SemaAMDGPU.h"
+#include "clang/Basic/DiagnosticFrontend.h"
 #include "clang/Basic/DiagnosticSema.h"
 #include "clang/Basic/TargetBuiltins.h"
-#include "clang/Frontend/FrontendDiagnostic.h"
 #include "clang/Sema/Ownership.h"
 #include "clang/Sema/Sema.h"
 #include "llvm/Support/AMDGPUAddrSpace.h"