we use several wlc440x which connect each with two links to two different core switches which are interconnected to each other; one of the core switches is stp root for all vlans.
Is there any need for the wlcs to have stp activated on their ports? As far as I know they don't bridge between their ports so in my opinion it's not obligatory.
Take a look at this link.... I never enabled STP on any of my WLC installs.