configs/ti_am64x_sk_defconfig: bump Linux version to 6.6.18

Tested-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Tested-by: Michael Trimarchi <michael@amarulasolutions.com>
Tested-by: Andreas Dannenberg <dannenberg@ti.com>
Tested-by: Gero Schwäricke <gero.schwaericke@grandcentrix.net>
Tested-by: Bryan Brattlof <bb@ti.com>
Reviewed-by: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Signed-off-by: Romain Naour <romain.naour@smile.fr>

board/ti/am64x-sk/patches/linux-headers/linux-headers.hash

@@ -0,0 +1 @@
+../linux/linux.hash

board/ti/am64x-sk/patches/linux/linux.hash

@@ -0,0 +1,2 @@
+# Locally calculated
+sha256  4e43d8c5fba14f7c82597838011648056487b7550fd83276ad534559e8499b1d  linux-6.6.18.tar.xz

configs/ti_am64x_sk_defconfig

@@ -1,13 +1,14 @@
 BR2_aarch64=y
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_4=y
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_6=y
 BR2_GLOBAL_PATCH_DIR="board/ti/am64x-sk/patches"
+BR2_DOWNLOAD_FORCE_CHECK_HASHES=y
 BR2_ROOTFS_POST_BUILD_SCRIPT="board/ti/common/am6xx/post-build.sh"
 BR2_ROOTFS_POST_BUILD_SCRIPT_ARGS="-c ttyS2,115200n8 -d k3-am642-sk.dtb -l am64x-sk-buildroot -r /dev/mmcblk1p2 -x earlycon=ns16550a,mmio32,0x02800000"
 BR2_ROOTFS_POST_IMAGE_SCRIPT="support/scripts/genimage.sh"
 BR2_ROOTFS_POST_IMAGE_SCRIPT_ARGS="-c board/ti/am64x-sk/genimage.cfg"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.4.16"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.6.18"
 BR2_LINUX_KERNEL_USE_ARCH_DEFAULT_CONFIG=y
 BR2_LINUX_KERNEL_DTS_SUPPORT=y
 BR2_LINUX_KERNEL_INTREE_DTS_NAME="ti/k3-am642-sk"