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>

drivers/video/c2p.h

@@ -1,7 +1,7 @@
 /*
  *  Fast C2P (Chunky-to-Planar) Conversion
  *
- *  Copyright (C) 2003 Geert Uytterhoeven
+ *  Copyright (C) 2003-2008 Geert Uytterhoeven
  *
  *  This file is subject to the terms and conditions of the GNU General Public
  *  License. See the file COPYING in the main directory of this archive
@@ -14,3 +14,6 @@ extern void c2p(void *dst, const void *src, u32 dx, u32 dy, u32 width,
 		u32 height, u32 dst_nextline, u32 dst_nextplane,
 		u32 src_nextline, u32 bpp);
 
+extern void c2p_iplan2(void *dst, const void *src, u32 dx, u32 dy, u32 width,
+		       u32 height, u32 dst_nextline, u32 src_nextline,
+		       u32 bpp);