Fix build break in SemaHLSL.cpp on MSVC 2022: warning C4715: 'getResourceClass': not all control paths return a value

Author: dpaoliello

clang/lib/Sema/SemaHLSL.cpp

@@ -102,6 +102,7 @@ static ResourceClass getResourceClass(RegisterType RT) {
     return ResourceClass::Sampler;
   case RegisterType::C:
   case RegisterType::I:
+  default:
     llvm_unreachable("unexpected RegisterType value");
   }
 }