configs/ci20_defconfig: bump Linux to version 6.1.81

The kernel build now requires FIT support in mkimage:

  ITB     arch/mips/boot/vmlinux.gz.itb
/home/peko/source/buildroot/output-ci20/host/bin/mkimage: unsupported type Flat Device Tree

So enable that.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

configs/ci20_defconfig

@@ -3,7 +3,7 @@ BR2_mipsel=y
 BR2_mips_xburst=y
 # BR2_MIPS_SOFT_FLOAT is not set
 BR2_KERNEL_HEADERS_AS_KERNEL=y
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_4=y
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_1=y
 
 # system
 BR2_TARGET_GENERIC_GETTY_PORT="ttyS4"
@@ -15,7 +15,7 @@ BR2_ROOTFS_POST_SCRIPT_ARGS="-c board/ci20/genimage.cfg"
 # kernel
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="5.4.254"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.1.81"
 BR2_LINUX_KERNEL_DEFCONFIG="ci20"
 BR2_LINUX_KERNEL_INSTALL_TARGET=y
 
@@ -29,6 +29,7 @@ BR2_TARGET_UBOOT_FORMAT_IMG=y
 BR2_TARGET_UBOOT_SPL=y
 BR2_TARGET_UBOOT_SPL_NAME="spl/u-boot-spl.bin"
 BR2_PACKAGE_HOST_UBOOT_TOOLS=y
+BR2_PACKAGE_HOST_UBOOT_TOOLS_FIT_SUPPORT=y
 BR2_PACKAGE_HOST_UBOOT_TOOLS_ENVIMAGE=y
 BR2_PACKAGE_HOST_UBOOT_TOOLS_ENVIMAGE_SOURCE="board/ci20/uboot-env.txt"
 BR2_PACKAGE_HOST_UBOOT_TOOLS_ENVIMAGE_SIZE="32768"