Move arch/ppc to arch/powerpc

As discussed on the list, move "arch/ppc" to "arch/powerpc" to
better match the Linux directory structure.

Please note that this patch also changes the "ppc" target in
MAKEALL to "powerpc" to match this new infrastructure. But "ppc"
is kept as an alias for now, to not break compatibility with
scripts using this name.

Signed-off-by: Stefan Roese <sr@denx.de>
Acked-by: Wolfgang Denk <wd@denx.de>
Acked-by: Detlev Zundel <dzu@denx.de>
Acked-by: Kim Phillips <kim.phillips@freescale.com>
Cc: Peter Tyser <ptyser@xes-inc.com>
Cc: Anatolij Gustschin <agust@denx.de>
diff --git a/doc/README.IPHASE4539 b/doc/README.IPHASE4539
index b804e06..c5146d9 100644
--- a/doc/README.IPHASE4539
+++ b/doc/README.IPHASE4539
@@ -333,7 +333,7 @@
 	$ make oldconfig
 	$ make dep
 	$ make uImage
-	$ cp -p arch/ppc/mbxboot/uImage /tftpboot
+	$ cp -p arch/powerpc/mbxboot/uImage /tftpboot
 
 	Load uImage via tftp and boot it.