bdinfo: microblaze: Use the generic bd command

bdinfo: microblaze: Use the generic bd command

Microblaze prints out ethernet and FDT information. This is useful to
most archs, so move it into the generic code and move microblaze over to
use it.

Note that FDT information is shown for all boards, since they should be
using device tree by now.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>