configs/imx6slevk: update the kernel to 6.6.51

Kernel 5.15 fails to build with GCC 13.

Update to kernel 6.6.51 to avoid the build failure.

Fixes: https://gitlab.com/buildroot.org/buildroot/-/jobs/7803199854

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 31ead1c082e6e75424e25707024cafa28806a381)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

configs/imx6slevk_defconfig

@@ -3,8 +3,8 @@ BR2_cortex_a9=y
 BR2_ARM_ENABLE_NEON=y
 BR2_ARM_ENABLE_VFP=y
 BR2_ARM_FPU_VFPV3=y
-# Linux headers same as kernel, a 5.15 series
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_15=y
+# Linux headers same as kernel, a 6.6 series
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_6=y
 BR2_TARGET_GENERIC_GETTY_PORT="ttymxc0"
 BR2_TARGET_ROOTFS_EXT2=y
 BR2_TARGET_ROOTFS_EXT2_4=y
@@ -16,10 +16,10 @@ BR2_TARGET_UBOOT_NEEDS_OPENSSL=y
 BR2_TARGET_UBOOT_FORMAT_IMX=y
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="5.15.11"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.6.51"
 BR2_LINUX_KERNEL_DEFCONFIG="imx_v6_v7"
 BR2_LINUX_KERNEL_DTS_SUPPORT=y
-BR2_LINUX_KERNEL_INTREE_DTS_NAME="imx6sl-evk"
+BR2_LINUX_KERNEL_INTREE_DTS_NAME="nxp/imx/imx6sl-evk"
 BR2_ROOTFS_POST_IMAGE_SCRIPT="board/freescale/common/imx/post-image.sh"
 # required tools to create the SD card image
 BR2_PACKAGE_HOST_DOSFSTOOLS=y