Camera: Reuse the ScreenNail's SurfaceTexture

The Camera Util class uses an unsynced mSurfaceTexture object. Remove this reference and
use the ScreenNail's one.
JIRA: CYAN-2079
Issue: https://jira.cyanogenmod.org/browse/CYAN-2079

Change-Id: I3143ce3288fbf9439fa3c6c06de34e672d415d78
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>
Camera: fix gfx undefined buffer issue

clear the render target before drawing, fix the undefined buffer
mess up issue of preview layer

Change-Id: I093fc0bdaf292fed2bc7f1a6d2678a94f25c9d55
CRs-fixed: 503216 506709
Merge branch 'cm-10.1' of git://github.com/CyanogenMod/android_packages_apps_Camera into jb-mv