This is a very old one. Doesn´t seem to go away. Reported this earlier
on 14th April:
http://lkml.org/lkml/2009/4/14/483,

CC [M]  drivers/mtd/maps/sbc8240.o
drivers/mtd/maps/sbc8240.c:31:1: warning: "DEBUG" redefined
In file included from drivers/mtd/maps/sbc8240.c:23:
include/linux/mtd/mtd.h:339:1: warning: this is the location of the
previous definition
drivers/mtd/maps/sbc8240.c: In function ‘init_sbc8240_mtd’:
drivers/mtd/maps/sbc8240.c:172: error: ‘sbc8240_mtd’ undeclared (first
use in this function)
drivers/mtd/maps/sbc8240.c:172: error: (Each undeclared identifier is
reported only once
drivers/mtd/maps/sbc8240.c:172: error: for each function it appears in.)
drivers/mtd/maps/sbc8240.c: In function ‘cleanup_sbc8240_mtd’:
drivers/mtd/maps/sbc8240.c:233: error: ‘sbc8240_mtd’ undeclared (first
use in this function)
make[3]: *** [drivers/mtd/maps/sbc8240.o] Error 1
make[2]: *** [drivers/mtd/maps] Error 2
make[1]: *** [drivers/mtd] Error 2
make: *** [drivers] Error 2
---

Regards--
Subrata