bdinfo: ppc: Move PPC-specific info into its own file

We don't really want to have PPC-specific code in a generic file. Create
a new arch-specific function to hold it, and move it into that.

Make the function weak so that any arch can implement it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 01c9dd5..f61809a 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -15,6 +15,8 @@
 endif
 endif
 
+obj-y	+= bdinfo.o
+
 ifdef MINIMAL
 obj-y += cache.o time.o
 ifndef CONFIG_TIMER