Fix alignment of cgroups info

[Furisto]

The format directive does not work when the type is not a string.
Before:

cgroup mounts
  blkio/sys/fs/cgroup/blkio
  cpu/sys/fs/cgroup/cpu,cpuacct
  cpuacct/sys/fs/cgroup/cpu,cpuacct
  cpuset/sys/fs/cgroup/cpuset
  devices/sys/fs/cgroup/devices
  freezer/sys/fs/cgroup/freezer
  hugetlb/sys/fs/cgroup/hugetlb
  memory/sys/fs/cgroup/memory
  net_cls/sys/fs/cgroup/net_cls,net_prio
  net_prio/sys/fs/cgroup/net_cls,net_prio
  pids/sys/fs/cgroup/pids
  unified         /sys/fs/cgroup/unified

After

cgroup mounts
  blkio           /sys/fs/cgroup/blkio
  cpu             /sys/fs/cgroup/cpu,cpuacct
  cpuacct         /sys/fs/cgroup/cpu,cpuacct
  cpuset          /sys/fs/cgroup/cpuset
  devices         /sys/fs/cgroup/devices
  freezer         /sys/fs/cgroup/freezer
  hugetlb         /sys/fs/cgroup/hugetlb
  memory          /sys/fs/cgroup/memory
  net_cls         /sys/fs/cgroup/net_cls,net_prio
  net_prio        /sys/fs/cgroup/net_cls,net_prio
  pids            /sys/fs/cgroup/pids
  unified         /sys/fs/cgroup/unified