kernel: kmod-dsa-ks8995: Backport DSA patches

kernel: kmod-dsa-ks8995: Backport DSA patches

Converts the KS8995 "phy" driver to a proper DSA switch.
Currently the upstream only supports the "none" tag
but this is a good improvement already.

Make the old module depend on kernel 6.6 and the new
one depend on !6.6.

The Realtek RTL8261n patch needs to be refreshed
because of textual dependencies.

Realtek RTL838x DSA and phy patches also have textual
dependencies and need to be refreshed.

The Mediatek in-flight DSA patch and related patches
also need to be rebased and refreshed.

Link: https://github.com/openwrt/openwrt/pull/19970
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>