configs/imx6ulevk: U-Boot needs host-dtc

Fixes:

  https://gitlab.com/buildroot.org/buildroot/-/jobs/55306824

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit e9151fd0be5369302933c9f0f26f97008786552d)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

configs/imx6ulevk_defconfig

@@ -25,6 +25,7 @@ BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2017.11"
 BR2_TARGET_UBOOT_FORMAT_IMG=y
 BR2_TARGET_UBOOT_SPL=y
 BR2_TARGET_UBOOT_SPL_NAME="SPL"
+BR2_TARGET_UBOOT_NEEDS_DTC=y
 
 # required tools to create the SD card image
 BR2_PACKAGE_HOST_DOSFSTOOLS=y