community/firmware-xiaomi-scorpio: Add QCA6174 board firmware

This significantly improves WiFi range and performance.

I originally refrained from adding the board firmware due to an issue that made it impossible to connect to networks (more details in this mail in ath10k mailing list), but it seems that this issue no longer exists, possibly due to some change in NetworkManager or somewhere in the kernel. I tried connecting to a router with both 2.4 and 5 GHz bands as well as my laptop set up as a hotspot, and both worked well.

(CC @MartijnBraam: maybe you can test with any access points you have just to make sure it doesn't break for anyone)