v4l2: ion: Do not set ION_FLAG_PROTECTED

Our OMX codecs are not ready for this and the
whole subsystem goes haywire when preparing
the codecs.

This mimics the behavior on Exynos5433.

Change-Id: Iceacf1296eee5f92dc545c34924add7385e1f5c0
Signed-off-by: Jesse Chan <jc@lineageos.org>