configs/cubieboard2: Update kernel to 4.18.14 and U-Boot to 2018.09

The board is well supported in upstream projects so let's update kernel
and U-Boot to the latest and greatest versions.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Erico Nunes <nunes.erico@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

configs/cubieboard2_defconfig

@@ -1,15 +1,15 @@
 BR2_arm=y
 BR2_cortex_a7=y
 BR2_ARM_FPU_NEON_VFPV4=y
-# Linux headers same as kernel, a 4.6 series
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_6=y
+# Linux headers same as kernel, a 4.18 series
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_18=y
 BR2_TARGET_GENERIC_HOSTNAME="Cubieboard2"
 BR2_TARGET_GENERIC_ISSUE="Welcome to Cubieboard2!"
 BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
 BR2_ROOTFS_POST_IMAGE_SCRIPT="board/cubietech/cubieboard2/post-image.sh"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.6"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.18.14"
 BR2_LINUX_KERNEL_DEFCONFIG="sunxi"
 BR2_LINUX_KERNEL_DTS_SUPPORT=y
 BR2_LINUX_KERNEL_INTREE_DTS_NAME="sun7i-a20-cubieboard2"
@@ -18,7 +18,7 @@ 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="2016.05"
+BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2018.09"
 BR2_TARGET_UBOOT_BOARD_DEFCONFIG="Cubieboard2"
 BR2_TARGET_UBOOT_NEEDS_DTC=y
 BR2_TARGET_UBOOT_SPL=y