Add missing async for tplink's async_setup_platform methods

[rytilahti]

thanks to @MartinHjelmare for spotting this, related to #21916

Breaking Change:

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Related issue (if applicable): fixes #

Pull request in home-assistant.io with documentation (if applicable): home-assistant/home-assistant.io#<home-assistant.io PR number goes here>

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[MartinHjelmare]

Great! Can be merged when build passes.

[balloob]

ok to merge when line length fixed.