msm: kgsl: Skip oob_perfcntr in slumber sequence

oob_perfcntr is bounded by the oob_gpu in slumber entry
sequnce. There is no impact by removing the oob_perfcntr
in this sequence. For oob_gpu and oob_perfcntr request
firmware just turns on the GX head switch. Hence skip the
oob_perfcntr request in slumber sequence, because perf
counters save will happen with the oob_gpu request.

Change-Id: I842f47a95dbb9a0bc5baf008c659d16c57c18594
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>