kernel-module-split add systemd modulesloaddir and modprobedir config

kernel-module-split add systemd modulesloaddir and modprobedir config

Because busybox doesn't support other path than /etc [1] we can't
change the default path unconditionally so change it only for systemd.

The modules-load.d [2] - Configure kernel modules to load at boot
should install their configuration files in /usr/lib/modules-load.d.

The modprobe.d [3] - Configuration directory for modprobe
should install their configuration files in /lib/modprobe.d

[1] https://git.busybox.net/busybox/tree/modutils/modprobe.c?id=669c40ed8ebf480c95ce36135104e474e361a7e6#n658
[2] https://man7.org/linux/man-pages/man5/modules-load.d.5.html
[3] https://man7.org/linux/man-pages/man5/modprobe.d.5.html

[YOCTO #12212] https://bugzilla.yoctoproject.org/show_bug.cgi?id=12212

Signed-off-by: Jose Quaresma <jose.quaresma@foundries.io>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>