Add support for Chrontel CH7033 VGA/DVI Encoder

[Lubomir Rintel]

Hi,

chained to this message is a driver for CH7033 along with device tree
binding docs.

Tested to work well on MMP3-based Dell Wyse 3020, some tweaks might be
needed for other configurations. There's not datasheet or programming
manual available.

Thanks,
Lubo