WIP: IPU and HDMI drivers for i.MX6

[Oleksandr Tymoshenko]

Hello,


    Last few months I've been working on IPU(video controller)/HDMI
support for i.MX6. This patch[1] is the first very limited
milestone. It contains more or less complete IPU driver, DVI mode
support for HDMI framer, and EDID handler. Missing part is pixel
clock management so at the moment driver relies on U-Boot to set
pixel clock for 1024x768 at 60 mode and it's the only supported mode
for now.

There seems to be several versions of DTS files for i.MX6 with
very different structure for HDMI-related nodes. Patch works only
with the version that is part of FreeBSD tree. 

Patch was tested on Hummingboard so any testing on other i.MX6
devices is appreciated

[1] https://people.freebsd.org/~gonzo/arm/patches/imx6-ipu-hdmi-20150719.diff