samsung-jflte: Modernize and fix splashscreen and osk-sdl

The splash screen no longer disappears instantly, full disk encryption is fully functional, and device-samsung-jflte is now modern (#8 (closed)).

I also noticed two weird color issues:

• When I use fbsplash to display a test image, red and blue are swapped. This isn't actually noticeable with the normal splash screen since it only uses black, white, and green.
• The background of osk-sdl should be #0099FF, but it looks more like #FF0099

The colors in XFCE4 look fine though, so I'm not too concerned.