sgxfreq: add sysfs interface to store frequency limit

Utilize all in kernel GPU frequencies but we can limit it to spesific
value. Replacement for the old in kernel gpu_oc sysfs interface to
verclock the GPU, have no harm to non-overclocked kernel

Change-Id: I2d9d1f05b0306de074ffdd327e9bf2a23c9d973f
tuna: only start the doze component after the screen has been turned off

Fixes screen off animation glitches.

Change-Id: I68424451acb957e8a2b71a10890208235e925bae