package/systemd: needs kernel options

according to https://wiki.gentoo.org/wiki/Systemd#Kernel



Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
[Peter: drop optional CGROUP_BPF / BPF_SYSCALL, unused POSIX_MQUEUE and
 DEVTMPFS which is already taken care of by linux.mk]
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>