drm/i915: use 120MHz refclk in PCH eDP case too

CPU eDP needs a different reference clock than PCH eDP, which uses the
standard PCH refclk of 120MHz.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_display.c

@@ -3625,7 +3625,8 @@ static int intel_crtc_mode_set(struct drm_crtc *crtc,
 			      refclk / 1000);
 	} else if (!IS_GEN2(dev)) {
 		refclk = 96000;
-		if (HAS_PCH_SPLIT(dev))
+		if (HAS_PCH_SPLIT(dev) &&
+		    (!has_edp_encoder || intel_encoder_is_pch_edp(&has_edp_encoder->base)))
 			refclk = 120000; /* 120Mhz refclk */
 	} else {
 		refclk = 48000;