Draft: d/patches: Use an overlay for the rpi 7" touch screen
In u-boot!80, u-boot is now able to auto-detect the rpi 7" touch screen.
To ease detection and loading the device tree bits for it when it is detected, switch to a device tree overlay.
The patch that added a device tree has been modified to add an overlay instead. It also now compiles the device tree and adds symbols (-@) in the rpi4 device tree (to be able to load the overlay)
Draft: Needs to be retested