inputselector: Deactivate and remove pad without the inputselector lock

inputselector: Deactivate and remove pad without the inputselector lock

Otherwise we might get deadlocks caused by lock order inversion:
During the chain function the stream lock is first locked and then the
inputselector lock. During pad release we first locked the inputselector
lock and then deactivating the pad would lock the stream lock.

There's no reason why the inputselector lock should be required while
deactivating and removing the pad, it's only needed before.

https://bugzilla.gnome.org/show_bug.cgi?id=704002