video: Add drm_dp_helper.h

This file (from Linux 3.17) provides defines for display port. Use it so
that our naming is consistent with Linux.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Tom Warren <twarren@nvidia.com>
1 file changed