Optimize fp touch to wake: Shortcut for report next draw

When telling window manager that Keyguard window is in the correct
state for a fp-touch-to-wake sequence, it takes more than 1 frame at
the moment because the signal that WM is waiting for the next draw
is delayed by one frame because it is posted at the end of the
runnable queue.

To correctly fix this, we should post it at the beginning at the
queue, but this is way too risky this late. Instead, add a isolated
SysUI hack to report it faster.

Bug: 23401557
Change-Id: Icf64101e27611c7c01d108123021b22186f1e70c