m_exprValue cannot be non-null here

...as, like the other private AstExpression::eval_* functions, eval_un_op is
only called from AstExpression::evaluate if m_exprValue is null

Change-Id: I812ea249d33a72f95b9692dc72ba6631ffbd4884

idlc/source/astexpression.cxx

@@ -1002,9 +1002,6 @@ AstExprValue* AstExpression::eval_bit_op()
 
 AstExprValue* AstExpression::eval_un_op()
 {
-    if (m_exprValue != NULL)
-        return m_exprValue;
-
     if (m_subExpr1 == NULL)
         return NULL;
     m_subExpr1->evaluate();