fbdev: c2p/atafb - Add support for Atari interleaved bitplanes

The c2p() for normal bitplanes is not suitable for interleaved bitplanes with
2 bytes of interleave, causing a garbled penguin logo. Add c2p_iplan2().

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

diff --cc drivers/video/Makefile
Simple merge

diff --cc drivers/video/atafb.c
Simple merge

diff --cc drivers/video/c2p.h
Simple merge

diff --cc drivers/video/c2p_core.h
Simple merge

diff --cc drivers/video/c2p_iplan2.c
Simple merge