tablet-x86uefi: support ath6kl wifi, fix scaling, support i2c touchscreens on boot

This fw is used by some tablets (specifically, my Dell Venue 8). For some reason or another, this fw is not included in the linux-firmware project, but is distributed directly by qualcomm.

This also adds drivers in the initramfs that enable i2c touchscreens (so fde can work), and removes forced scaling for phoc/phosh (see commit message for details)

This should probably be squashed before merging, but separate commits make it easier to review (I hope) 😄

(cc @iliketwertles)