msm: kgsl: Fix enabling power counters during device start.

Fixed the mask to enabled power counters during device start.
These counters are used for performance measurements and DCVS.
DCVS later in the code reinitializes the counters correctly.
This fix is required for performance measurements.

Change-Id: I08d3a184b5120c5251060bb9c5f080af0167732d
Signed-off-by: Tarun Karra <tkarra@codeaurora.org>