Fix config_flow error from dlna_dmr for UPnP discovery info containing a single service

[chishm]

Proposed change

The SSDP config flow handler for dlna_dmr crashes when a device only defines a single service in its UPnP description. This is a fix for that case.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes dlna_dmr issues in HA core logs #67521
• This PR is related to issue:
• Link to documentation pull request:

Checklist

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[probot-home-assistant]

Hey there @StevenLooman, mind taking a look at this pull request as it has been labeled with an integration (dlna_dmr) you are listed as a code owner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[Kane610]

Looks good to me!

[chishm]

Thank you both for the fast review and merge. These changes should be ok to cherry pick into the 2022.4 release.