Fix color setting of tplink lights

[amelchio]

Description:

This hopefully fixes TPLink lights after the hue/sat update. I noticed a few other issues as well.

I do not have hardware to test this so please review closely.

• Cast hue/sat to integers like before the hue/sat conversion.
• Remove ATTR_KELVIN as it should not reach platforms.
• Allow setting of brightness and color in a single call.
• Use current/provided brightness (and not a constant) for HSV.

CC @Arkadyf, @armills

Related issue (if applicable): fixes #13924, also reported in #11288 (comment)

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox.

[balloob]

I'm removing this from the milestone as the release is going out today and no one with hardware seems to have tested this.

[Arkadyf]

I was able to load this tplink.py and can confirm that it fixed my color issue.
Tested on LB230 lights, HA version 0.67.1.

• I'm new to this, so in case it matters, to test this I created a a tplink.py file in the following location:
  /config/custom_components/light/
  Then I copy-pasted the contents of amelchio's edit. Restarted HA, and the lights started working with color.

[amelchio]

@balloob That's fine, I agree with not adding untested code to the final release. As it is tested now and a fairly serious bug for those affected, are you okay with adding it to 0.68.1 even if the regression happened a few releases ago?

@Arkadyf Thanks for testing. That is a fine way to do it with minimal impact to the running system.

BTW, I found an existing issue for this bug: #13924

[balloob]

Yes, fine with 0.68.1