Gallery2: camera: disable all camera controls ASAP when swtich the camera

Camera switch button is a pieItem, there is a fadeInOut animation for these
kinds of menus. And the onClick event deliver to upper layer happens after
the end of the animation which lasts 600ms. We should add another event
callback before the animation to disalbe all camera controls as soon as
possible.

Change-Id: Iddcb9e9452aa0ff6ea8485c08c9c56b067995fb5