package/systemd: set cgroups default-hierarchy to unified

Use the unified hierarchy, which is systemds default since v243.
The biggest holdover was docker which now supports the unified
layout.

Note that systemd will automatically fallback to hybrid if the
kernel is too old or the unified hierarchy fails for other reasons.

Signed-off-by: Norbert Lange <[email protected]>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <[email protected]>

package/systemd/systemd.mk

@@ -46,7 +46,7 @@ SYSTEMD_SELINUX_MODULES = systemd udev xdg
 SYSTEMD_PROVIDES = udev
 
 SYSTEMD_CONF_OPTS += \
-	-Ddefault-hierarchy=hybrid \
+	-Ddefault-hierarchy=unified \
 	-Didn=true \
 	-Dima=false \
 	-Dkexec-path=/usr/sbin/kexec \