drm/i915: Check VBT for eDP ports on VLV

VLV can have eDP on either port B or C, or even both. Based on the
VBT spec, intel_dpd_is_edp() should work on VLV too, assuming we
check the correct ports.

So instead of hardcoding port D, rename the function to
intel_dp_is_edp() and pass the port as a parameter, and use it
on VLV ports B and C.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=71051
Tested-by: Robert Hooker <robert.hooker@canonical.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
[danvet: Wrestle the patch to apply and compile properly.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ddi.c

@@ -173,7 +173,7 @@ static void intel_prepare_ddi_buffers(struct drm_device *dev, enum port port)
 		ddi_translations = ddi_translations_dp;
 		break;
 	case PORT_D:
-		if (intel_dpd_is_edp(dev))
+		if (intel_dp_is_edp(dev, PORT_D))
 			ddi_translations = ddi_translations_edp;
 		else
 			ddi_translations = ddi_translations_dp;