dragon: sensor: Set FIFO size properly to pass batching CTS tests.

Update in CTS tests check for proper batching.
Forgot to reduce the FIFO size by 33%: the EC has a high water mark at
33%, issuing an interrupt at around 1400 events.

BUG=b:27534791
TEST=Witch fixes,
run cts -s 6612345600 -k -c android.hardware.cts.SensorBatchingTests
passes - execpt for AOSP sensors, another issue.

Change-Id: I250fae5b94094c41b87fa2862a70227386d1c17d
Signed-off-by: Gwendal Grignou <gwendal@google.com>
1 file changed