msm: kgsl: Bump the frequency all the way to turbo for long IBs

Any IB that hasn't gone idle in an idle period and has spent the
majority of that time with the GPU busy should go as fast as
possible.  The most common use case where this is seen is for
OpenCL kernels.

CRs-fixed: 527197
Change-Id: Idf3fd0bfddc1cd1ac00f87dd72e403b81d70b170
Signed-off-by: Lucille Sylvester <lsylvest@codeaurora.org>