layerscape: switch to Linux 6.12
Linux 6.12 has been validated on Layerscape platforms, including NXP
reference boards and multiple custom designs. Tests covered system
boot, networking, storage, and common peripherals, with no regressions
observed.
Enable 6.12 as the default to continue broader testing and integration.
Signed-off-by: Pawel Dembicki <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20614
Signed-off-by: Christian Marangi <[email protected]>