ath79: rename patchset and kernel configs to 6.18
This is a preparation for 6.18 kernel support. It can help us
track the files history by using the Git tool.
Signed-off-by: Shiji Yang <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/22771
Signed-off-by: Nick Hainke <[email protected]>