Update MTD to that of Linux 2.6.22.1

A lot changed in the Linux MTD code, since it was last ported from
Linux to U-Boot. This patch takes U-Boot NAND support to the level
of Linux 2.6.22.1 and will enable support for very large NAND devices
(4KB pages) and ease the compatibility between U-Boot and Linux
filesystems.

This patch is tested on two custom boards with PPC and ARM
processors running YAFFS in U-Boot and Linux using gcc-4.1.2
cross compilers.

MAKEALL ppc/arm has some issues:
 * DOC/OneNand/nand_spl is not building (I have not tried porting
   these parts, and since I do not have any HW and I am not familiar
   with this code/HW I think its best left to someone else.)

Except for the issues mentioned above, I have ported all drivers
necessary to run MAKEALL ppc/arm without errors and warnings. Many
drivers were trivial to port, but some were not so trivial. The
following drivers must be examined carefully and maybe rewritten to
some degree:
 cpu/ppc4xx/ndfc.c
 cpu/arm926ejs/davinci/nand.c
 board/delta/nand.c
 board/zylonite/nand.c

Signed-off-by: William Juul <william.juul@tandberg.com>
Signed-off-by: Stig Olsen <stig.olsen@tandberg.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>

include/common.h

@@ -119,11 +119,13 @@ typedef volatile unsigned char	vu_char;
 #define debugX(level,fmt,args...)
 #endif	/* DEBUG */
 
+#ifndef BUG
 #define BUG() do { \
 	printf("BUG: failure at %s:%d/%s()!\n", __FILE__, __LINE__, __FUNCTION__); \
 	panic("BUG!"); \
 } while (0)
 #define BUG_ON(condition) do { if (unlikely((condition)!=0)) BUG(); } while(0)
+#endif /* BUG */
 
 typedef void (interrupt_handler_t)(void *);