msm: kgsl: Turn off power resources only if SP/TP is collapsed

A430 has capability of collapsing SP/TP when idle. Check for the
power collapse status before turning off power resources.

Change-Id: Id67627820b18f7d89dbdf4fc00cfedf8f65e4ac2
Signed-off-by: Suman Tatiraju <sumant@codeaurora.org>