dmesg - flush stdout before sleeping

* Flush output before sleeping when dmesg -f is specified.
cyapa - Implement power save mode, try to fix boot issue (Acer c720 chromebook)

* Implement power save mode when the pad hasn't been touched for 10 seconds.
  Return to full power on any activity.

* Try to fix an issue when cyapa is loaded from /boot/loader.conf or built
  into the kernel.  For some reason cyapa polls that it isn't running but
  we'd already gone through the bootstrap sequence and determined that it
  was running.  Why it stops is not known but it appears doing a status query
  after init completion puts it in the right state.