fix: Fix GPU temperature conversion in the popup chart

[maxd]

This PR fixes GPU temperature conversion in the popup chart after an incorrect fix in the fb63ece commit related to the #1809 issue.

Before this fix the GPU chart show incorrect temperature value:

As you can see it shows 0C instead of 48C and 3300F instead of 118F.

After this fix it should show the correct values:

[exelban]

hi. Please use temperature function to convert the temperature.

[BenTalagan]

Hi, any update on this PR ? It adresses an annoying bug, and it'd be awesome to get it finalized ! Thx for the hard work.

[maxd]

@exelban The temperature function is responsible for converting and formatting. I can't use it here because I only need the converting part. I suppose there are no ways to solve described problem without splitting this function into two.

So, I decided to update my PR and refactor this function. Now, the temperature function will be responsible for converting to a selected temperature unit, and the format extension function will be responsible for formatting.

Is this an acceptable solution, or can you provide a better one?