drm/i915: Add the support of eDP on DP-D for Ibex/CPT

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=27220

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Tested-by: Jan-Hendrik Zab <jan@jhz.name>
Tested-by: Templar <templar@rshc.de>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f879589..926470d 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3452,7 +3452,7 @@
 				temp |= PIPE_8BPC;
 			else
 				temp |= PIPE_6BPC;
-		} else if (is_edp) {
+		} else if (is_edp || (is_dp && intel_pch_has_edp(crtc))) {
 			switch (dev_priv->edp_bpp/3) {
 			case 8:
 				temp |= PIPE_8BPC;