thermal: remove redundant cdev_to_watch registration

cdev_to_watch fd causes pollOnce function return immediatly.
Because thermalhal does not monitor cdev status now,
so remove cdev_to_watch fd to avoid threadLoop busy problem.

Bug: 151897840
Test: Verified thermalhal notifythrottling via emul_temp
      thermalhal will not keep busy.
Signed-off-by: TeYuan Wang <kamewang@google.com>

(cherry picked from commit b59c54e95b6bca8a765f8940d477101f8acbd949)
Change-Id: If6234b43a82d61c36fddff4c66be6eb4434fdb7d
3 files changed