msm: kgsl: Prevent device start after it is already started

Check if device is already started in high priority workqueue thread,
this check prevents calling device start after it is already started,
thereby avoiding unpredictable behavior.

Change-Id: Iffcd065f8c02746d168c8e5779d10d4b0e2404a9
Signed-off-by: Tarun Karra <tkarra@codeaurora.org>
Revert "msm: kgsl: Lower devfreq polling interval to reasonable 100ms"

This reverts commit 3eb8d4b42ff6ad384007746435e97f3403e84ba8.
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: hotplug: Remove deprecated msm_cpufreq_set_freq_limits