msm: kgsl: Start the sleep timer after recovery has completed

Start the sleep timer if recovery from hang is successful.
This prevents GPU from entering low power states during
recovery.

Change-Id: Icb021f1b1bfae7876394fa572acd156115372ac3
Signed-off-by: Tarun Karra <tkarra@codeaurora.org>
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>