SemaHLSL header was included twice (#2388)

Removed repeated include of #include "clang/Sema/SemaHLSL.h"

tools/clang/lib/Sema/SemaHLSL.cpp

@@ -30,7 +30,6 @@
 #include "clang/Sema/Template.h"
 #include "clang/Sema/TemplateDeduction.h"
 #include "clang/Sema/SemaHLSL.h"
-#include "clang/Sema/SemaHLSL.h"
 #include "dxc/Support/Global.h"
 #include "dxc/Support/WinIncludes.h"
 #include "dxc/Support/WinAdapter.h"