config: Move CONFIG_DEFAULT_FDT_FILE to defconfigs

- Add DEFAULT_FDT_FILE kconfig entry
- Move CONFIG_DEFAULT_FDT_FILE from include/configs to defconfigs

Cc: Tom Rini <trini@konsulko.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/configs/zc5202_defconfig b/configs/zc5202_defconfig
index 8d3f1df..c979854 100644
--- a/configs/zc5202_defconfig
+++ b/configs/zc5202_defconfig
@@ -13,6 +13,7 @@
 CONFIG_SPL_SPI_SUPPORT=y
 CONFIG_SPL_WATCHDOG_SUPPORT=y
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=arch/arm/imx-common/spl_sd.cfg,MX6Q"
+CONFIG_DEFAULT_FDT_FILE="imx6q-zc5202.dtb"
 CONFIG_BOOTDELAY=3
 CONFIG_SPL=y
 CONFIG_CMD_MMC=y