Fix rockblox on all 160x128x2 and 160x128x16 targets. They used the mono bitmap intended for m:robe100 as a native one, making the background looking odd and crashing the sim. Bitmaps for monochrome targets used like native bitmaps shouldn't reside in bitmaps/mono, as that's asking for confusion.
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17629 a1c6a512-1295-4272-9138-f99709370657