Torch: apply wakelocks to sysfs nodes

Assuming the kernel is setup to disable LED flashlight on suspend, let's
make sure we don't hit suspend when the LED is active. This extends
the wakelock to affect sysfs toggles in addition to the existing
wakelock on the camera interface.

Change-Id: I8997e70396eeb3cc16a5f39ca4c5e59b4aafefdb