MPC512x: workaround data corruption for unaligned local bus accesses

Commit 460c2ce3 "MPC5200: workaround data corruption for unaligned
local bus accesses" fixed the problem for MPC5200 only, but MPC512x is
affected as well, so apply the same fix here, too.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Detlev Zundel <dzu@denx.de>
Cc: Anatolij Gustschin <agust@denx.de>
Acked-by: Detlev Zundel <dzu@denx.de>