drm_hwcomposer: uses edid DTD to get better estimate of dpi
Edid are not the most reliable when it comes to panel size, however it seems like preferred DTD are slightly more reliable. This change moves from the drm parse edid display size to the first preferred DTD to try improve dpi accuracy. If no preferred DTD is available we still fallback to the display size.
Change-Id: Ibcc95da9f38ba74e9b95b9d68587b38efbed8de2 signed-off-by: Lucas Berthou berlu@google.com