Verified with 4.8.0-fc.9

Per reproduction steps in PR#2601 (thanks @jkyros!), upgrade from 4.5 -> 4.8 and check the `maxUnavailable` value of the `machine-config-daemon` DaemonSet:


- Installed 4.5.40

```
$ oc get co/machine-config
NAME             VERSION   AVAILABLE   PROGRESSING   DEGRADED   SINCE
machine-config   4.5.40    True        False         False      62m
$ oc get -n openshift-machine-config-operator ds/machine-config-daemon -o json | jq .spec.updateStrategy
{
  "rollingUpdate": {
    "maxUnavailable": 1
  },
  "type": "RollingUpdate"
}
```
- Upgraded to 4.6.32

```
$ oc get clusterversion
NAME      VERSION   AVAILABLE   PROGRESSING   SINCE   STATUS
version   4.6.32    True        False         72s     Cluster version is 4.6.32
$ oc get -n openshift-machine-config-operator ds/machine-config-daemon -o json | jq .spec.updateStrategy
{
  "rollingUpdate": {
    "maxUnavailable": 1
  },
  "type": "RollingUpdate"
}
```

- Upgraded to 4.7.16

$ oc get clusterversion
NAME      VERSION   AVAILABLE   PROGRESSING   SINCE   STATUS
version   4.7.16    True        False         3h46m   Cluster version is 4.7.16
[miabbott@toolbox (container) ~/openshift-cluster-installs/4.5.40 ]$ oc get -n openshift-machine-config-operator ds/machine-config-daemon -o json | jq .spec.updateStrategy
{
  "rollingUpdate": {
    "maxUnavailable": 1
  },
  "type": "RollingUpdate"
}

- Upgraded to 4.8.0-fc.9

```
$ oc get clusterversion
NAME      VERSION      AVAILABLE   PROGRESSING   SINCE   STATUS
version   4.8.0-fc.9   True        False         110s    Cluster version is 4.8.0-fc.9
$ oc get -n openshift-machine-config-operator ds/machine-config-daemon -o json | jq .spec.updateStrategy
{
  "rollingUpdate": {
    "maxSurge": 0,
    "maxUnavailable": "10%"
  },
  "type": "RollingUpdate"
}
```

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Moderate: OpenShift Container Platform 4.8.2 bug fix and security update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2021:2438