Add overlay for raspberry pi 7inch touchscreen MIPI DSI to 5B+

[aalaei]

In Overlays, There is a support for the RADXA Rock 5B but not for the 5B+(for connection to 7 inch display), despite both having the same SoC. After reviewing the datasheet, I couldn't find any differences between the two. I was wondering why support is not available for the 5B+.

Is it possible to add support for the 5B+ as well?

[RadxaYuntian]

No one has verified whether it will work. You can test it yourself with rsetup to manually loading the overlay from this repo.