HLSL: Non-functional: warning fix, remove unused member.

Two non-functional changes:

1. Remove flattenLevel, which is unneeded since at or around d1be7545c6.

2. Fix build warining about unused variable in executeInitializer.

hlsl/hlslParseHelper.cpp

@@ -7553,7 +7553,6 @@ TIntermNode* HlslParseContext::executeInitializer(const TSourceLoc& loc, TInterm
     TType skeletalType;
     skeletalType.shallowCopy(variable->getType());
     skeletalType.getQualifier().makeTemporary();
-    TIntermAggregate* initializerList = nullptr;
     if (initializer->getAsAggregate() && initializer->getAsAggregate()->getOp() == EOpNull)
         initializer = convertInitializerList(loc, skeletalType, initializer, nullptr);
     if (initializer == nullptr) {