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/include/configs/barco.h b/include/configs/barco.h
index e00f84a..b1af701 100644
--- a/include/configs/barco.h
+++ b/include/configs/barco.h
@@ -136,6 +136,8 @@
 #define CONFIG_LOGBUFFER
 #ifdef	CONFIG_LOGBUFFER
 #define CONFIG_SYS_STDOUT_ADDR		0x1FFC000
+#define CONFIG_SYS_POST_WORD_ADDR	\
+		(CONFIG_SYS_SDRAM_BASE + CONFIG_SYS_MAX_RAM_SIZE - 4)
 #else
 #define CONFIG_SYS_STDOUT_ADDR		0x2B9000
 #endif