GPU OC: Smoother Ramp up

* Rather than having two 320 MHz steps lets go from 320 MHz to 389 MHz then to 450 MHz so it's not as crazy of a jump

Change-Id: Ifd299079feaa2d2d67810af7f0311f50c8c6d715
Signed-off-by: Chester Kener <Cl3Kener@gmail.com>