Pin to the latest stable 5.10.18 release in order to ensure patches
don't unexpectedly conflict in newer linux versions.
The wi-fi firmware has since been upstreamed to the `linux-firmware`
repo, and as such is now available via `enableRedistributableFirmware`.
As a result we can remove the old expr that pulled the firmware from
kvalo's github.
Also removes two patches that have since been upstreamed.
0359644c22