ath79: switch default kernel to 6.12
We have not received any negative feedback in the past three months.
It's time to switch the default kernel to 6.12.
Signed-off-by: Shiji Yang <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/19821
Signed-off-by: Nick Hainke <[email protected]>