msm: kgsl: Delay the first devfreq status read

No reason to read status when there hasn't been any activity
yet.  Wait at least one sample period after the GPU has been
turned on before pinging devfreq to read status.

Change-Id: I65633a76f0bbf0bded51f1d6ffbb7808d57f7884
Signed-off-by: Lucille Sylvester <lsylvest@codeaurora.org>