toradex: set default dhcp distroboot scriptname

Use the same name of DHCP Distroboot script as in regular eMMC case.

Signed-off-by: Igor Opaniuk <igor.opaniuk@toradex.com>
Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
diff --git a/include/configs/colibri-imx6ull.h b/include/configs/colibri-imx6ull.h
index 281815e..fa4f8ce 100644
--- a/include/configs/colibri-imx6ull.h
+++ b/include/configs/colibri-imx6ull.h
@@ -101,6 +101,7 @@
 	NFS_BOOTCMD \
 	UBI_BOOTCMD \
 	UBOOT_UPDATE \
+	"boot_script_dhcp=boot.scr\0" \
 	"bootubipart=ubi\0" \
 	"console=ttymxc0\0" \
 	"defargs=user_debug=30\0" \