fix: Specify the wireless.wifi-device.type as mac80211

Before this commit, we do not add a `type` to the wifi-device(s) we
create from scratch; we hope that they'd be available and already set
to `mac80211`.

For example, if we do not have a section in `/etc/config/wireless` for
the phy at sysfs path `ffe09000.pcie...`, creating one with Ansible
with this inventory variable:

```yaml
        - name: radio1
          path: ffe09000.pcie/pci9000:00/9000:00:00.0/9000:01:00.0
          template: ath9k_2
          channel: 6
```

would give us

```/etc/config/wireless
config wifi-device 'radio1'
        option htmode 'HT20'
        option band '2g'
        option channel '6'
        option country 'US'
        option disabled '0'
        option path 'ffe09000.pcie/pci9000:00/9000:00:00.0/9000:01:00.0'
```

... and not:

```/etc/config/wireless
config wifi-device 'radio1'
        option type 'mac80211'
        option htmode 'HT20'
        option band '2g'
        option channel '6'
        option country 'US'
        option disabled '0'
        option path 'ffe09000.pcie/pci9000:00/9000:00:00.0/9000:01:00.0'
```

Force the section as mac80211. This has no support for non-mac80211,
cfg80211-only drivers -- that's fine, as we only see (in practice)
ath9k, ath10k, ath11k and mt76 among the routers we're configuring
with ansible-labb-wifi.

(cherry picked from commit a4b505a4e6c218de4ec02f06f3eb58e97bdb517c)

roles/netconfig/tasks/main.yml

@@ -38,6 +38,7 @@
       path: "{{ item.path }}"
     name: "{{ item.name }}"
     value:
+      type: "mac80211" # they'd BETTER be.
       band: "{{ item.band | default(wifi_device[item.template].band) | default() }}"
       channel: "{{ item.channel | default(wifi_device[item.template].channel) }}"
       country: "{{ item.country | default(wifi_device[item.template].country) }}"