core: support cgroup v2 device controller

Cgroup v2 provides the eBPF-based device controller, which isn't currently
supported by systemd. This commit aims to provide such support.

There are no user-visible changes, just the device policy and whitelist
start working if cgroup v2 is used.

src/basic/cgroup-util.h

@@ -30,6 +30,7 @@ typedef enum CGroupController {
 
         /* BPF-based pseudo-controllers, v2 only */
         CGROUP_CONTROLLER_BPF_FIREWALL,
+        CGROUP_CONTROLLER_BPF_DEVICES,
 
         _CGROUP_CONTROLLER_MAX,
         _CGROUP_CONTROLLER_INVALID = -1,
@@ -47,6 +48,7 @@ typedef enum CGroupMask {
         CGROUP_MASK_DEVICES = CGROUP_CONTROLLER_TO_MASK(CGROUP_CONTROLLER_DEVICES),
         CGROUP_MASK_PIDS = CGROUP_CONTROLLER_TO_MASK(CGROUP_CONTROLLER_PIDS),
         CGROUP_MASK_BPF_FIREWALL = CGROUP_CONTROLLER_TO_MASK(CGROUP_CONTROLLER_BPF_FIREWALL),
+        CGROUP_MASK_BPF_DEVICES = CGROUP_CONTROLLER_TO_MASK(CGROUP_CONTROLLER_BPF_DEVICES),
         _CGROUP_MASK_ALL = CGROUP_CONTROLLER_TO_MASK(_CGROUP_CONTROLLER_MAX) - 1
 } CGroupMask;