configs/friendlyarm_nanopi_r2s: bump to kernel 6.18.18 and U-Boot 2026.01

This commit:
- bumps the Linux kernel to 6.18.18
- bumps the U-Boot to 2026.01
- switches to a stable glibc Bootlin external toolchain
- enables force hashes check
- enlarge the rootfs size to 256M

The updated U-Boot should also fix the CI build of the board.

Fixes: https://gitlab.com/buildroot.org/buildroot/-/jobs/13458392713

Run-tested on the board.

Signed-off-by: Dong Wang <wangdong115@foxmail.com>
[Julien:
 - remove .checkpackageignore entry to fix check-package error
 - move uboot.hash in its correct directory
]
Signed-off-by: Julien Olivain <ju.o@free.fr>

.checkpackageignore

@@ -94,7 +94,6 @@ configs/ci20_defconfig lib_defconfig.ForceCheckHash
 configs/freescale_p1025twr_defconfig lib_defconfig.ForceCheckHash
 configs/freescale_t1040d4rdb_defconfig lib_defconfig.ForceCheckHash
 configs/freescale_t2080_qds_rdb_defconfig lib_defconfig.ForceCheckHash
-configs/friendlyarm_nanopi_r2s_defconfig lib_defconfig.ForceCheckHash
 configs/globalscale_espressobin_defconfig lib_defconfig.ForceCheckHash
 configs/imx23evk_defconfig lib_defconfig.ForceCheckHash
 configs/imx6-sabreauto_defconfig lib_defconfig.ForceCheckHash

board/friendlyarm/nanopi-r2s/patches/linux/linux.hash

@@ -0,0 +1,2 @@
+# From https://www.kernel.org/pub/linux/kernel/v6.x/sha256sums.asc
+sha256  f4855f382c1b735c84072bdef36db5bcd5dc7b0c37e42f5104317149a0a486ef  linux-6.18.18.tar.xz

board/friendlyarm/nanopi-r2s/patches/uboot/uboot.hash

@@ -0,0 +1,2 @@
+# Locally calculated
+sha256  b60d5865cefdbc75da8da4156c56c458e00de75a49b80c1a2e58a96e30ad0d54  u-boot-2026.01.tar.bz2

configs/friendlyarm_nanopi_r2s_defconfig

@@ -1,6 +1,10 @@
 BR2_aarch64=y
 BR2_ARM_FPU_VFPV4=y
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_12=y
+BR2_TOOLCHAIN_EXTERNAL=y
+BR2_TOOLCHAIN_EXTERNAL_BOOTLIN=y
+BR2_TOOLCHAIN_EXTERNAL_BOOTLIN_AARCH64_GLIBC_STABLE=y
+BR2_GLOBAL_PATCH_DIR="board/friendlyarm/nanopi-r2s/patches"
+BR2_DOWNLOAD_FORCE_CHECK_HASHES=y
 BR2_TARGET_GENERIC_HOSTNAME="rk3328-nanopi-r2s"
 BR2_TARGET_GENERIC_ISSUE="Welcome to Nanopi R2S RK3328"
 BR2_ROOTFS_POST_BUILD_SCRIPT="board/friendlyarm/nanopi-r2s/post-build.sh"
@@ -8,7 +12,7 @@ BR2_ROOTFS_POST_IMAGE_SCRIPT="support/scripts/genimage.sh"
 BR2_ROOTFS_POST_SCRIPT_ARGS="-c board/friendlyarm/nanopi-r2s/genimage.cfg"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.12.13"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.18.18"
 BR2_LINUX_KERNEL_USE_ARCH_DEFAULT_CONFIG=y
 BR2_LINUX_KERNEL_DTS_SUPPORT=y
 BR2_LINUX_KERNEL_INTREE_DTS_NAME="rockchip/rk3328-nanopi-r2s"
@@ -16,7 +20,7 @@ BR2_LINUX_KERNEL_INSTALL_TARGET=y
 BR2_LINUX_KERNEL_NEEDS_HOST_OPENSSL=y
 BR2_TARGET_ROOTFS_EXT2=y
 BR2_TARGET_ROOTFS_EXT2_4=y
-BR2_TARGET_ROOTFS_EXT2_SIZE="120M"
+BR2_TARGET_ROOTFS_EXT2_SIZE="256M"
 BR2_TARGET_ARM_TRUSTED_FIRMWARE=y
 BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_VERSION=y
 BR2_TARGET_ARM_TRUSTED_FIRMWARE_CUSTOM_VERSION_VALUE="v2.12"
@@ -26,7 +30,7 @@ BR2_TARGET_ARM_TRUSTED_FIRMWARE_NEEDS_ARM32_TOOLCHAIN=y
 BR2_TARGET_UBOOT=y
 BR2_TARGET_UBOOT_BUILD_SYSTEM_KCONFIG=y
 BR2_TARGET_UBOOT_CUSTOM_VERSION=y
-BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2024.10"
+BR2_TARGET_UBOOT_CUSTOM_VERSION_VALUE="2026.01"
 BR2_TARGET_UBOOT_BOARD_DEFCONFIG="nanopi-r2s-rk3328"
 BR2_TARGET_UBOOT_NEEDS_DTC=y
 BR2_TARGET_UBOOT_NEEDS_PYLIBFDT=y