configs/liteboard: bump U-Boot to 2020.04

Signed-off-by: Bartosz Bilas <b.bilas@grinn-global.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

configs/grinn_liteboard_defconfig

@@ -16,7 +16,7 @@ BR2_TARGET_ROOTFS_EXT2_4=y
 BR2_TARGET_UBOOT=y
 BR2_TARGET_UBOOT_BUILD_SYSTEM_KCONFIG=y
 BR2_TARGET_UBOOT_CUSTOM_VERSION=y
-BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2020.01"
+BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2020.04"
 BR2_TARGET_UBOOT_BOARD_DEFCONFIG="liteboard"
 BR2_TARGET_UBOOT_FORMAT_IMG=y
 BR2_TARGET_UBOOT_SPL=y