Fixing buienradar sensor config key error

[hmmbob]

Description:

Fixing warning about unsupported config key 'name' in Buienradar sensor, whilst it was actually supported (but just not validated).

Related issue (if applicable): n/a

Pull request in home-assistant.io with documentation (if applicable): n/a

Example entry for sensors.yaml:

### This will set the sensor name to sensor.volkel_[monitored_condition], 
### i.e. sensor.volkel_temperature
- platform: buienradar
  name: 'volkel'
  monitored_conditions:
    - stationname
    - condition
    - temperature

### This will set the sensor name to the default 'br': 
### sensor.br_[monitored_condition], i.e. sensor.br_temperature
- platform: buienradar
  monitored_conditions:
    - stationname
    - condition
    - temperature

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.

[fabaff]

Thanks 🐦