Telephony: fix typo

Change-Id: Ic13235744fca561cff4d49ae5c799420c30a3840
hwui: Don't discard framebuffer on exynos4

The layers gets empty/not cleaned and redrawn on top of the preview,
causing beautiful glitch on homescreen, and drawing black instead
of transparency.

Change-Id: I633b104224c73c625f1193ee3dde41823cddc5bf