gralloc/gralloc960: Drop linux/ion.h references as its gone

Bionic dropped the linux/ion.h header, so make sure we don't
try to include it and cause build errors.

Change-Id: I6af15f1bd2b53e7d5dd29a93295bfc09df36ab62
Signed-off-by: John Stultz <john.stultz@linaro.org>
5 files changed