Quicksettings: Fix battery tile showing 0% in certain conditions

Battery tile would show 0% sometimes because
the callback isn't sent until battery was updated.

Instead we store state via global variables and force
the first update.

Also includes simplification of code.

Change-Id: Ia346c883308cbdab5a7cccdbd579e4d605b831e8
Signed-off-by: Evan Anderson <evan@thelinuxman.us>