Don't read configs on every touch event for double tap to sleep

Got the idea from Dave Kessler - VanirAOSP

Change-Id: Ice60896dbd0bcd2de1dbff07baa7bf60af0cad58
[1/2] Statusbar: Make double tap gesture configurable

Change-Id: I6864f54bd4fa1616910135efd82015e9d8c08659

Observe double tap gesture setting changes

Change-Id: I51f0e909c1c62eb860297cbdf26cffdb92969a60