package/mender_x86_64_efi_defconfig: bump kernel to 6.12.28

linux.conf does not change after manually checking the output of
`make savedefconfig` in the kernel source directory.

Signed-off-by: Adam Duskett <adam.duskett@amarulasolutions.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

configs/mender_x86_64_efi_defconfig

@@ -1,5 +1,5 @@
 BR2_x86_64=y
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_6=y
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_12=y
 BR2_INIT_SYSV=y
 BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_EUDEV=y
 BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
@@ -9,7 +9,7 @@ BR2_ROOTFS_POST_IMAGE_SCRIPT="board/mender/x86_64/post-image-efi.sh"
 BR2_ROOTFS_POST_SCRIPT_ARGS="--data-part-size=32M --device-type=buildroot-x86_64 --artifact-name=1.0"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.6.49"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.12.28"
 BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
 BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/mender/x86_64/linux.config"
 BR2_LINUX_KERNEL_INSTALL_TARGET=y