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: NWeijie Gao <weijie.gao@mediatek.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>

configs/mt7623n_bpir2_defconfig

@@ -26,7 +26,7 @@ CONFIG_CMD_READ=y
 CONFIG_CMD_PING=y
 CONFIG_CMD_FAT=y
 CONFIG_CMD_FS_GENERIC=y
-CONFIG_OF_EMBED=y
+CONFIG_OF_SEPARATE=y
 CONFIG_DEFAULT_DEVICE_TREE="mt7623n-bananapi-bpi-r2"
 CONFIG_NET_RANDOM_ETHADDR=y
 CONFIG_REGMAP=y

configs/mt7629_rfb_defconfig

@@ -29,7 +29,7 @@ CONFIG_CMD_SF_TEST=y
 # CONFIG_CMD_NFS is not set
 CONFIG_CMD_PING=y
 # CONFIG_PARTITIONS is not set
-CONFIG_OF_EMBED=y
+CONFIG_OF_SEPARATE=y
 CONFIG_DEFAULT_DEVICE_TREE="mt7629-rfb"
 CONFIG_OF_SPL_REMOVE_PROPS="pinctrl-0 pinctrl-names clock-names interrupt-parent assigned-clocks assigned-clock-parents"
 CONFIG_NET_RANDOM_ETHADDR=y