Add config to support iotedge

Change-Id: I699e62dd776a1d2dec21ec13540c03e106814df1
Reviewed-on: https://tp-biosrd-v02/gerrit/84607
Reviewed-by: Alex Cheng(鄭富元) <Alex_Cheng@asus.com>
Tested-by: Alex Cheng(鄭富元) <Alex_Cheng@asus.com>

Author: Lyle_Lin

arch/arm/configs/miniarm-rk3288_defconfig

@@ -894,3 +894,4 @@ CONFIG_CAN=y
 CONFIG_CAN_DEV=y
 CONFIG_CAN_MCP251X=y
 CONFIG_SND_SOC_GOOGLEVOICEHAT_CARD=y
+CONFIG_OVERLAY_FS=y