'Rockboxed' theme: while working on the bitmap strips for the bigger colour displays...

'Rockboxed' theme: while working on the bitmap strips for the bigger colour displays I noticed that they had an image for 'unknown' or broken battery state. Even though it's probably seldom displayed at all, I thought other ports could have it too. Only the small colour ones for now because I had no idea how to 'translate' this style into a mono or greyscale icon.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17074 a1c6a512-1295-4272-9138-f99709370657