CHROMIUM: rockchip: rk3399: bump DMC opp voltages

This bumps the 928MHz operating point by 50mV and the 800MHz operating
point by 25mV for the DMC to fix bit flip issues.

BUG=chrome-os-partner:62513
TEST=stressapptest -M 1500 -s 10000

Change-Id: I0705c20a13a3a61cb0ed144feb09d7e6d1f98671
Signed-off-by: Derek Basehore <dbasehore@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/440433
Reviewed-by: Douglas Anderson <dianders@chromium.org>
(cherry picked from commit f9c10367bd43a5b0695a66e27a4cb6d7c62faddb)
Reviewed-on: https://chromium-review.googlesource.com/441311
Tested-by: Douglas Anderson <dianders@chromium.org>