kernel: bump 6.6 to 6.6.81

kernel: bump 6.6 to 6.6.81

Changelog: https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.6.81

All patches automatically rebased.

For x86, CONFIG_MICROCODE_LATE_FORCE_MINREV was introduced in this bump
with hrecommendation to enable it[1].

1. https://web.git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/diff/arch/x86/Kconfig?id=v6.6.81&id2=v6.6.80

Build system: x86/64
Build-tested: bcm27xx/bcm2712, flogic/xiaomi_redmi-router-ax6000-ubootmod, ramips/tplink_archer-a6-v3
Run-tested: bcm27xx/bcm2712, flogic/xiaomi_redmi-router-ax6000-ubootmod, ramips/tplink_archer-a6-v3

Signed-off-by: John Audia <therealgraysky@proton.me>
Link: https://github.com/openwrt/openwrt/pull/18188
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>