camera: allow proper preview window updates to be disabled

This causes issues with various video chat apps for devices such as
Sensation and possibly others using HTC MSM8660 camera HAL.

This is needed in Jellybean too.
See: https://github.com/CyanogenMod/android_frameworks_base/commit/795b92632696bcb307332ce32d682664b8c21d94

Change-Id: Ib4ae37df214b774e521b5bfad55f9b4558da148f