uboot-phytec

configs: MediaTek: use OF_SEPARATE instead of OF_EMBED

This patch replace OF_EMBED with OF_SEPARATE of defconfig files of
MediaTek boards because now OF_EMBED is only used for debugging purpose.

Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
Reviewed-by: Simon Glass <sjg@chromium.org>