configs/freescale_t1040d4rdb: bump linux kernel to 6.12.27

Since commit [1] "package/binutils: make 2.43 the default version",
the freescale_t1040d4rdb_defconfig fails to build the Linux
kernel, with the error:

    arch/powerpc/boot/util.S: Assembler messages:
    arch/powerpc/boot/util.S:49: Error: junk at end of line, first unrecognized character is `0'
    arch/powerpc/boot/util.S:54: Error: syntax error; found `b', expected `,'
    arch/powerpc/boot/util.S:54: Error: junk at end of line: `b'

This commit fixes the issue by updating the Linux kernel to the latest
LTS version.

Fixes:
https://gitlab.com/buildroot.org/buildroot/-/jobs/9967089767

[1] https://gitlab.com/buildroot.org/buildroot/-/commit/360fd01de20eb42aa0e6b5e9f7b37eaa104c6fc9

Signed-off-by: Julien Olivain <ju.o@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 6ad80909205f43aabe3a6ec7ebf875f1f01d23ad)
Signed-off-by: Thomas Perale <thomas.perale@mind.be>

configs/freescale_t1040d4rdb_defconfig

@@ -1,10 +1,10 @@
 BR2_powerpc64=y
 BR2_powerpc_e5500=y
-BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_15=y
+BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_12=y
 BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
 BR2_LINUX_KERNEL=y
 BR2_LINUX_KERNEL_CUSTOM_VERSION=y
-BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.15.7"
+BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.12.27"
 BR2_LINUX_KERNEL_DEFCONFIG="corenet64_smp"
 BR2_LINUX_KERNEL_DTS_SUPPORT=y
 BR2_LINUX_KERNEL_INTREE_DTS_NAME="fsl/t1040d4rdb"