This PKGBUILD generates two packages that contain the patchset from Kalle Valo's
ath11k-qca6390-bringup branch.
Build and install them in your Arch or Manjaro Linux, and then you'll get the stable WiFi support in your Dell XPS 13" 9310:
$ makepkg -s
...
$ pacman -U linux510-qca6390-*.pkg.tar.*
...