Draft: testing/samsung-v1awifi: add mainline package

Thanks to @grimler for helping me with this port.

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Device boots and USB Networking works because the tablet is detected by the PC.

However, nothing else works: SSH gives connection reset (probably due to the cable not being genuine from manufacturer), no working display, no WiFi, etc.

In addition, the device is not booting with the linux-postmarketos-exynos5 kernel, as nothing is detected on the computer.

The mainline package has the same configuration as the linux-postmarketos-exynos5 kernel, but it only contains the patches required for Samsung Exynos 5420 tablets.