Remove things related to gBatteryCurrent to save ~148 bytes.

[prokrypt]

That's quite a few bytes used just to display a charging indicator for USB-C when there is already a hardware indicator built into the radio.
It doesn't work on my KSUN UV60D anyways, and possibly some other UV-K5's...

[armel]

I'll take a look 👀

[prokrypt]

you can take a look at all of my changes @ main...prokrypt:uv-k5-firmware-custom:main but be warned that it's messy 😆

[prokrypt]

You know you want some of that extra-precise, extra-useless battery voltage readings! 😁

Just kidding. It's a byproduct of making the percentage steps "smoother" (no more skipped numbers).