msm: kgsl: Only wake GPU upon ioctl receipt when it isn't awake

The overhead of queuing the power-on worker every time there's an ioctl
received is significant due to the frequency of GPU ioctls. To mitigate
the high overhead, only fire up the power-on worker when the GPU isn't
active.

Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com>
Signed-off-by: Danny Lin <danny@kdrag0n.dev>