msm: kgsl: Enable POPP functionality at GPU turbo

Gather the GPU's sleep statistics to make a more informed
decision about when trying a POPP push may be appropriate.
Previously pushes were forbidden while in turbo, now allow
them when there appears to be significant idle.

Change-Id: I8f2f74365051ceea005e3b7cf35d65025882ec7c
Signed-off-by: Lucille Sylvester <lsylvest@codeaurora.org>