New issue by adrian-bl on void-packages repository

https://github.com/void-linux/void-packages/issues/24657

Description:
### System

* xuname:  
Void 5.4.59_1 armv7l Unknown uptodate rFFFF

* package:  
rpi-kernel-5.4.59_1

### Expected behavior

The 5.4 *rbpi* kernel seems to lack support for memory cgroups: this makes it impossible to run any software which requires `/sys/fs/cgroup/memory` to be present.

This breaks nomad for me, but i suppose that docker would also be affected.

Note that the old 4.19.x kernel supported memory cgroups.

I suppose that adding

```
CONFIG_MEMCG=y
CONFIG_MEMCG_SWAP=y
CONFIG_MEMCG_KMEM=y
```

to the kernel config would be sufficient (this is how the x86_64 kernel is configured).


### Steps to reproduce the behavior

```
$ grep cgroup/memory /proc/mounts | wc -l
0
```

### Expected behavior

```
grep cgroup/memory /proc/mounts
cgroup /sys/fs/cgroup/memory cgroup rw,relatime,memory 0 0
```