Add DD-WRT icon and logo

[Deinara]

Proposed change

Add icon and logo for DD-WRT.
The available icon is low resolution, so hDPI icons are not included

Type of change

• Add a new logo or icon for a new integration
• Add a missing icon or logo for an existing integration
• Replace an existing icon or logo with a higher quality version
• Removing an icon or logo

Additional information

• This PR fixes or closes issue: fixes DD-WRT is missing brand images #178
• Link to code base pull request:
• Link to documentation pull request: Removed DD-WRT icon reference home-assistant.io#12773
• Link to integration documentation on our website: https://www.home-assistant.io/integrations/ddwrt/

Checklist

• The added/replaced image(s) are PNG
• Icon image size is 256x256px (icon.png)
• hDPI icon image size is 512x512px for (icon@2x.png)
• Logo image size has min 128px, but max 256px, on the shortest side (logo.png)
• hDPI logo image size has min 256px, but max 512px, on the shortest side (logo@2x.png)

[cogneato]

Yeah let's just go for it. Thanks, @Deinara