configs/odroidxu4: remove defconfig, broken

This defconfig no longer builds:

  https://gitlab.com/buildroot.org/buildroot/-/jobs/11012273936

It has been broken for over 2 months:

  https://gitlab.com/buildroot.org/buildroot/-/jobs?name=T%3Dodroidxu4&kind=BUILD

Most likely the U-Boot version used is no longer compatible with
recent toolchains.

Unless a fix is provided, this defconfig will be removed.

Cc: Pierre Crokaert <pct@crookies.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Arnout Vandecappelle <arnout@rnout.be>
(cherry picked from commit 585527b872)
Signed-off-by: Titouan Christophe <titouan.christophe@mind.be>

configs/odroidxu4_defconfig

@@ -1,27 +0,0 @@
-BR2_arm=y
-BR2_cortex_a7=y
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_14=y
-BR2_ROOTFS_POST_IMAGE_SCRIPT="board/hardkernel/odroidxu4/post-image.sh"
-BR2_LINUX_KERNEL=y
-BR2_LINUX_KERNEL_CUSTOM_GIT=y
-BR2_LINUX_KERNEL_CUSTOM_REPO_URL="https://github.com/hardkernel/linux.git"
-BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="4.14.16-104"
-BR2_LINUX_KERNEL_DEFCONFIG="odroidxu4"
-BR2_LINUX_KERNEL_DTS_SUPPORT=y
-BR2_LINUX_KERNEL_INTREE_DTS_NAME="exynos5422-odroidxu4"
-BR2_TARGET_ROOTFS_EXT2=y
-BR2_TARGET_ROOTFS_EXT2_4=y
-# BR2_TARGET_ROOTFS_TAR is not set
-BR2_TARGET_UBOOT=y
-BR2_TARGET_UBOOT_BUILD_SYSTEM_KCONFIG=y
-BR2_TARGET_UBOOT_CUSTOM_GIT=y
-BR2_TARGET_UBOOT_CUSTOM_REPO_URL="https://github.com/hardkernel/u-boot.git"
-BR2_TARGET_UBOOT_CUSTOM_REPO_VERSION="88af53fbcef8386cb4d5f04c19f4b2bcb69e90ca"
-BR2_TARGET_UBOOT_BOARD_DEFCONFIG="odroid-xu4"
-BR2_TARGET_UBOOT_NEEDS_DTC=y
-BR2_TARGET_UBOOT_FORMAT_DTB_BIN=y
-BR2_TARGET_UBOOT_SPL=y
-BR2_TARGET_UBOOT_SPL_NAME="sd_fuse/bl1.bin.hardkernel sd_fuse/bl2.bin.hardkernel.720k_uboot sd_fuse/tzsw.bin.hardkernel "
-BR2_PACKAGE_HOST_DOSFSTOOLS=y
-BR2_PACKAGE_HOST_GENIMAGE=y
-BR2_PACKAGE_HOST_MTOOLS=y