configs/orangepi_pc_plus_defconfig: bump BSP versions

Bump Linux to 5.12.2 and U-Boot to 2021.04.

Introduce minor cleanup: use SPL options instead of custom image options
for combined SPL image.

Signed-off-by: Sergey Matyukevich <geomatsi@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

configs/orangepi_pc_plus_defconfig

@@ -2,13 +2,13 @@ BR2_arm=y
 BR2_cortex_a7=y
 BR2_ARM_FPU_VFPV4=y
 BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_MDEV=y
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_3=y
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_12=y
 BR2_TARGET_GENERIC_HOSTNAME="OrangePi_PC_Plus"
 BR2_TARGET_GENERIC_ISSUE="Welcome to Buildroot for the Orange Pi PC Plus"
 BR2_SYSTEM_DHCP="eth0"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="5.3.8"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="5.12.2"
 BR2_LINUX_KERNEL_DEFCONFIG="sunxi"
 BR2_LINUX_KERNEL_DTS_SUPPORT=y
 BR2_LINUX_KERNEL_INTREE_DTS_NAME="sun8i-h3-orangepi-pc-plus"
@@ -20,12 +20,13 @@ 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="2019.10"
+BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2021.04"
 BR2_TARGET_UBOOT_BOARD_DEFCONFIG="orangepi_pc_plus"
 BR2_TARGET_UBOOT_NEEDS_DTC=y
+BR2_TARGET_UBOOT_NEEDS_PYTHON3=y
 BR2_TARGET_UBOOT_NEEDS_PYLIBFDT=y
-BR2_TARGET_UBOOT_FORMAT_CUSTOM=y
-BR2_TARGET_UBOOT_FORMAT_CUSTOM_NAME="u-boot-sunxi-with-spl.bin"
+BR2_TARGET_UBOOT_SPL=y
+BR2_TARGET_UBOOT_SPL_NAME="u-boot-sunxi-with-spl.bin"
 BR2_PACKAGE_HOST_UBOOT_TOOLS_BOOT_SCRIPT=y
 BR2_PACKAGE_HOST_UBOOT_TOOLS_BOOT_SCRIPT_SOURCE="board/orangepi/orangepi-pc-plus/boot.cmd"
 BR2_PACKAGE_HOST_DOSFSTOOLS=y