Convert analogix_dp.txt to yaml for use as common document.

Changed:
  Relexed requirements
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/489e7bd3-fa26-885f-4104-8b0b29aa4f2b@gmail.com