Fix cgroup hugetlb size prefix for kB

The hugetlb cgroup control files (introduced here in 2012:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=abb8206cb0773)
use "KB" and not "kB"
(https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/hugetlb_cgroup.c?h=v5.0#n349).

The behavior in the kernel has not changed since the introduction, and
the current code using "kB" will therefore fail on devices with small
amounts of ram (see
kubernetes#77169) running a kernel
with config flag CONFIG_HUGETLBFS=y

As seen from the code in "mem_fmt" inside hugetlb_cgroup.c, only "KB",
"MB" and "GB" are used, so the others may be removed as well.

Here is a real world example of the files inside the
"/sys/kernel/mm/hugepages/" directory:
- "hugepages-64kB"
- "hugepages-2048kB"
- "hugepages-32768kB"
- "hugepages-1048576kB"

And the corresponding cgroup files:
- "hugetlb.64KB._____"
- "hugetlb.2MB._____"
- "hugetlb.32MB._____"
- "hugetlb.1GB._____"

This does also require the following changes in runc:
opencontainers/runc#2065

Signed-off-by: Odin Ugedal <odin@ugedal.com>

Author: odinuge

pkg/kubelet/cm/cgroup_manager_linux.go

@@ -51,7 +51,7 @@ const (
 
 // hugePageSizeList is useful for converting to the hugetlb canonical unit
 // which is what is expected when interacting with libcontainer
-var hugePageSizeList = []string{"B", "kB", "MB", "GB", "TB", "PB"}
+var hugePageSizeList = []string{"B", "KB", "MB", "GB", "TB", "PB"}
 
 var RootCgroupName = CgroupName([]string{})