drm/i915: compute the target_clock for edp directly

... instead of abusing mode->clock by storing it in there - we
shouldn't touch that one at all. This patch is the first prep step to
constify the mode argument of the intel_dp_mode_fixup function.

The next patch will stop us from modifying mode->clock.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index ade98e0..ae7c623 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -152,6 +152,18 @@
 		*link_bw = 270000;
 }
 
+int
+intel_edp_target_clock(struct intel_encoder *intel_encoder,
+		       struct drm_display_mode *mode)
+{
+	struct intel_dp *intel_dp = container_of(intel_encoder, struct intel_dp, base);
+
+	if (intel_dp->panel_fixed_mode)
+		return intel_dp->panel_fixed_mode->clock;
+	else
+		return mode->clock;
+}
+
 static int
 intel_dp_max_lane_count(struct intel_dp *intel_dp)
 {