Camera: Fix out-of-order operations while setting up the editor

The buffer's producer is created by the cache pipeline generation,
so verifying that it isn't null before calling compute() is wrong.

This breaks a few devices, and should actually break them all, so
fix it; only check if getProducer() is valid after running setProducer()

Change-Id: I9d7d03fa9c9eb7063daef2ae28a78cd70b7a5ef3
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_packages_apps_Gallery2 into cm-11.0

Conflicts:
	src/com/android/gallery3d/filtershow/pipeline/UpdatePreviewTask.java