sepolicy support for cgroup v2

cgroup v2 is going to be used for freezer v2 support. The cgroup v2 hiearchy
will be mounted by init under /sys/fs/cgroup hence proper access rights
are necessary for sysfs. After mounting, the cgroup v2 kernfs will use
the label cgroup_v2 and system_manager will handle the freezer

Bug: 154548692
Test: verified that files undes sysfs and cgroup v2 kernfs are accessed
as required to allow proper functioning for the freezer.

Change-Id: Idfb3f6e77b60dad032d1e306d2f9b58cd5775960
diff --git a/private/genfs_contexts b/private/genfs_contexts
index e67c5d3..433abbc 100644
--- a/private/genfs_contexts
+++ b/private/genfs_contexts
@@ -103,7 +103,7 @@
 # selinuxfs booleans can be individually labeled.
 genfscon selinuxfs / u:object_r:selinuxfs:s0
 genfscon cgroup / u:object_r:cgroup:s0
-genfscon cgroup2 / u:object_r:cgroup_bpf:s0
+genfscon cgroup2 / u:object_r:cgroup_v2:s0
 # sysfs labels can be set by userspace.
 genfscon sysfs / u:object_r:sysfs:s0
 genfscon sysfs /devices/system/cpu u:object_r:sysfs_devices_system_cpu:s0