bdinfo: m68k: Move m68k-specific info into its own file

We don't really want to have m68k-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>
Tested-by: Angelo Dureghello <angelo.dureghello@timesys.com>
Tested-by: Angelo Dureghello <angelo.dureghello@timesys.com>
diff --git a/arch/m68k/lib/Makefile b/arch/m68k/lib/Makefile
index a040f40..b66d66a 100644
--- a/arch/m68k/lib/Makefile
+++ b/arch/m68k/lib/Makefile
@@ -7,6 +7,7 @@
 ## if the user asked for it
 lib-$(CONFIG_USE_PRIVATE_LIBGCC) += lshrdi3.o muldi3.o ashldi3.o
 
+obj-y	+= bdinfo.o
 obj-$(CONFIG_CMD_BOOTM) += bootm.o
 obj-y	+= cache.o
 obj-y	+= interrupts.o