Move lib_$ARCH directories to arch/$ARCH/lib

Also move lib_$ARCH/config.mk to arch/$ARCH/config.mk

This change is intended to clean up the top-level directory structure
and more closely mimic Linux's directory organization.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
diff --git a/board/RPXlite/u-boot.lds b/board/RPXlite/u-boot.lds
index 47247ec..c354ff8 100644
--- a/board/RPXlite/u-boot.lds
+++ b/board/RPXlite/u-boot.lds
@@ -57,7 +57,7 @@
 
     cpu/mpc8xx/start.o	(.text)
     common/dlmalloc.o	(.text)
-    lib_ppc/ppcstring.o	(.text)
+    arch/ppc/lib/ppcstring.o	(.text)
     lib_generic/vsprintf.o	(.text)
     lib_generic/crc32.o		(.text)
     lib_generic/zlib.o		(.text)