PM: devfreq: conservative: Return 0 if GPU just started

Bailing out early is perfectly fine, so do not trigger an error in
update_devfreq.
msm: kgsl: Report correct GPU frequency in sysfs
msm: kgsl: Export device state to devfreq
PM / devfreq: Get priv data for msm-adreno-tz governor from dev_profile

The devfreq infrastructure has several bugs and general design flaws
with private governor data support. As a workaround the msm-adreno-tz
governor gets it's private data from the device driver by doing a
container_of on the dev_profile registered by the device driver.

[myfluxi: Adapt to 8974, add yet unused stuff for conservative governor]

Change-Id: Ib9dffd063fe3aa5cfd55727d41f7633e88b3f998
Signed-off-by: Vladimir Razgulin <vrazguli@codeaurora.org>