A20 HDMI and lima support

Created by: enunes

This pull request contains patches to enable HDMI support and add the lima device bindings to the Allwinner A20. The first ones were backported from upstream linux-next and I included the information about the respective cherry-picked patch. These can be dropped in a further upstream rebase (4.15 I believe since they are not on a 4.14 rc). Then there are some that I picked from mripard's tree which are some work to enable the HDMI support on the A10 and A20 SoCs. I couldn't find them in upstream but they are interesting to have in linux-lima since these SoCs have a mali400 and an upstream working display driver (sun4i-drm). So we can use them to test lima rendering to a display. Finally, there are some that I wrote to port the required device tree nodes for a working HDMI from the sun4i to the sun7i (A20), and also to add the mali400 device node.