POST cleanup.

- Revives POST for blackfin arch;
- Removes redundant code:
     arch/blackfin/lib/post.c
     arch/powerpc/cpu/ppc4xx/commproc.c
     arch/powerpc/cpu/mpc512x/common.c
- fixes up the post_word_{load|store} usage.

Signed-off-by: Michael Zaidman <michael.zaidman@gmail.com>
Acked-by: Detlev Zundel <dzu@denx.de>
Tested-by: Anatolij Gustschin <agust@denx.de>

List of the maintainers of the affected by patch boards:
Cc: Stephan Linz <linz@li-pro.net>
Cc: Denis Peter <d.peter@mpl.ch>
Cc: Matthias Fuchs <matthias.fuchs@esd-electronics.com>
Cc: Peter Tyser <ptyser@xes-inc.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Niklaus Giger <niklaus.giger@netstal.com>
Cc: Larry Johnson <lrj@acm.org>
Cc: Feng Kan <fkan@amcc.com>
diff --git a/arch/blackfin/lib/Makefile b/arch/blackfin/lib/Makefile
index 3bdba75..a18bbd6 100644
--- a/arch/blackfin/lib/Makefile
+++ b/arch/blackfin/lib/Makefile
@@ -46,7 +46,7 @@
 COBJS-$(CONFIG_CMD_CACHE_DUMP) += cmd_cache_dump.o
 COBJS-$(CONFIG_CMD_KGDB) += kgdb.o
 COBJS-y	+= muldi3.o
-COBJS-$(CONFIG_POST) += post.o tests.o
+COBJS-$(CONFIG_POST_ALT_LIST) += tests.o
 COBJS-y	+= string.o
 
 SRCS	:= $(SOBJS-y:.o=.S) $(COBJS-y:.o=.c)