Do not allow wallpapers that are too large

DisplayListCanvas, that draws Bitmaps on the Android framework,
has a bitmap size limit. Let's respect the limit to guarantee
that SystemUI won't crashloop when a bitmap is over 100MB

Test: manual, setting wallpaper
Change-Id: Iff91e73722a912efe095f80e263e160cc2456a11
Fixes: 111330638