sony-coconut: Added 16-bit color depth workaround

Hello everybody. I am the only contributor for the device sony-coconut (Sony Xperia Live With Walkman), previously known as @praticamentetilde. It seems due to negligence from my side that I forgot to add in my previous PR the 16-bit color depth workaround, which is definitely needed for this device to display proper colors.

P.S.: I know it has been a while since I contributed, but I just started out university and I have been quite busy.