LVGL Certified boards - add display interface

Hi LVGL, as a suggestion it would be interesting for me to add the display interface (eg: SPI, parallel, etc…) to the certified boards list, it help to compare. I believe all on the list are non-SPI but still help to know which interface it is.

It’s really not consistent but for some boards on the blog you can find an “Interface” bullet point.

Anyway, I will add it to the website too.