This one adds support for eDP that connected on PCH DP-D port
instead of CPU DP-A port, and only DP-D port could be used for eDP.

https://bugs.freedesktop.org/show_bug.cgi?id=27220Signed-off-by: NZhao Yakui <yakui.zhao@intel.com>
Tested-by: NJan-Hendrik Zab <jan@jhz.name>
Tested-by: NTemplar <templar@rshc.de>
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: NEric Anholt <eric@anholt.net>