[Clang][AArch64] Fix -Wcovered-switch-default warning (SemaARM)

Author: SpencerAbson

clang/include/clang/Basic/TargetBuiltins.h

@@ -236,6 +236,7 @@ namespace clang {
       case Poly128:
         return 128;
       }
+      llvm_unreachable("Invalid NeonTypeFlag!");
     }
   };
 

clang/lib/Sema/SemaARM.cpp

@@ -504,9 +504,6 @@ bool SemaARM::CheckImmediateArg(CallExpr *TheCall, unsigned CheckTy,
         SemaRef.BuiltinConstantArgMultiple(TheCall, ArgIdx, 2))
       return true;
     break;
-  default:
-    llvm_unreachable("Invalid immediate range typeflag!");
-    break;
   }
   return false;
 }