kmod: Enable xz support by default

kmod: Enable xz support by default

RPi kernel has started building compressed kernel modules by default
starting 5.15, currenrly therefore meta-raspberrypi kernels are unable
to load kernel modules since kmod and kmod-native do not entertain xz
compressed modules. There is a fix proposed in meta-raspberrypi [1]
but the fix is needed for native and nativesdk recipes as well, perhaps
its best to enable it here for best out of box experience with
meta-raspberrypi

[1] https://github.com/agherzan/meta-raspberrypi/pull/1056

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>