Update checkother.cpp [skip ci]

Author: chrchr-github

lib/checkother.cpp

@@ -640,7 +640,7 @@ void CheckOtherImpl::checkRedundantAssignment()
                     if (Token::Match(rhs, ":: %name%") && rhs->hasKnownIntValue())
                         return ChildrenToVisit::none;
                     if (rhs->isCast())
-                        return ChildrenToVisit::op2;
+                        return rhs->astOperand2() ? ChildrenToVisit::op2 : ChildrenToVisit::op1;
                     trivial = false;
                     return ChildrenToVisit::done;
                 });