Power widget: Resize ring_on and ring_vibrate_on drawbles slightly

Made the icons slightly smaller to fit the silent-drawable based on
user feedback. I agree it was a bit large before.

Thanks to dvtonder for the originals.

stat_silent.png is only resaved so that it once again works in PS.

Change-Id: Ic54f97eba6163d1f828a6bea1f4f14dba9c57b9c