drm/i915/bdw: Broadwell has a max port clock of 300Mhz on HDMI

Just like HSW.

This means we can scan out a mode with a 300Mhz pixel clock with a depth
of 24 bits, but only a 200Mhz one with a 36bits depth.
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NBen Widawsky <ben@bwidawsk.net>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_hdmi.c

@@ -847,7 +847,7 @@ static int hdmi_portclock_limit(struct intel_hdmi *hdmi)
 
 	if (IS_G4X(dev))
 		return 165000;
-	else if (IS_HASWELL(dev))
+	else if (IS_HASWELL(dev) || INTEL_INFO(dev)->gen >= 8)
 		return 300000;
 	else
 		return 225000;