light.tplink: initialize supported features in setup_platform

[rytilahti]

Description:

Fetch supported features already in setup_platform, avoids calling {min,max}_minreds (thanks to #15484 ) causing a zerodivisionerror on bulbs not supporting temperature changing.

Related issue (if applicable): fixes #15339

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

Example entry for configuration.yaml (if applicable):

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated in home-assistant.github.io

If the code communicates with devices, web services, or third-party tools:

• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies are only imported inside functions that use them (example).
• New or updated dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.
• New files were added to .coveragerc.

If the code does not interact with devices:

• Tests have been added to verify that the new code works.

[amelchio]

Why not keep this call inside the TPLinkSmartBulb class?

[rytilahti]

Because I/O is not allowed inside constructor, and if those features are not set min_mireds may be called before there an initial update has happened. Or that's my understanding at least.

[MartinHjelmare]

In async_update_ha_state the call to update will be done before any entity properties are accessed. I propose to revert all changes except on line 45, which will make sure that update is called before the first state update, and that supported features should be up to date.

[rytilahti]

Hmm, if that's the case, there's then no need for this PR at all actually and the problem itself should have been fixed by #15484, as the second parameter was True already.