Simplify MQTT light brightness logic

[LordMike]

Proposed change

Simplify the code in a branch where the value checked will always be None. In this branch, self._brightness is always None, hence the removed code is unnecessary.

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

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

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

• Documentation added/updated for www.home-assistant.io

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

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

The integration reached or maintains the following Integration Quality Scale:

• No score or internal
• 🥈 Silver
• 🥇 Gold
• 🏆 Platinum

[homeassistant]

Hi @LordMike,

It seems you haven't yet signed a CLA. Please do so here.

Once you do that we will be able to review and accept this pull request.

Thanks!

[probot-home-assistant]

Hey there @home-assistant/core, @emontnemery, mind taking a look at this pull request as its been labeled with a integration (mqtt) you are listed as a codeowner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[LordMike]

Note: Python is not my first language. I was merely reading the code to understand more of why the mqtt integration "misbehaved".. (it didn't).

[MartinHjelmare]

Looks good!

[MartinHjelmare]

Please run black code formatter from the project root and commit the changes.

black --fast homeassistant

[frenck]

Thanks, @LordMike 👍