powerpc/km82xx: remove 82xx specific functions from common.c

Common code should be valid for more than one architecture,
therefore the km82xx specific code was removed from common.c.

Signed-off-by: Holger Brunck <holger.brunck@keymile.com>
Signed-off-by: Valentin Longchamp <valentin.longchamp@keymile.com>
cc: Heiko Schocher <hs@denx.de>
cc: Wolfgang Denk <wd@denx.de>