samsung-coreprimevelte: Implement U-Boot
This MR packages U-Boot for samsung-coreprimevelte
and modifies the device package to use it. Besides this, the following QoL changes are made:
- Upgrade kernel to 6.13-rc4. No new hardware support is added, but numerous patches have been upstreamed and 2 quirks which are rendered useless with the introduction of U-Boot are dropped.
- Fix small regression causing the OpenRC service for enabling the downstream WLAN driver to be installed even with the mainline kernel.
- Fix the software keyboard in the debug shell.