teclast-x80pro: drop device

Kernel doesn't compile anymore, and it doesn't seem worth fixing it again. The kernel has been added in 2017 as a stock mainline kernel from that time with only two patches and wasn't maintained since then, looking at git log --follow it was only patched to fix it up when it didn't build.

As the device is a generic x86_64 tablet: if somebody has that particular device, try to get the generic device-tablet-x64uefi running instead.

Related: https://wiki.postmarketos.org/wiki/Teclast_X80_Pro_(teclast-x80pro)