drm/i915/ehl: Update voltage level checks

The bspec was recently updated with new cdclk -> voltage level tables to
accommodate the new 324/326.4 cdclk values.

Bspec: 21809
Fixes: 63c9dae ("drm/i915/ehl: Add voltage level requirement table")
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Cc: Bob Paauwe <bob.j.paauwe@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191118164412.26216-1-matthew.d.roper@intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>

drivers/gpu/drm/i915/display/intel_cdclk.c

@@ -1273,7 +1273,9 @@ static u8 icl_calc_voltage_level(int cdclk)
 
 static u8 ehl_calc_voltage_level(int cdclk)
 {
-	if (cdclk > 312000)
+	if (cdclk > 326400)
+		return 3;
+	else if (cdclk > 312000)
 		return 2;
 	else if (cdclk > 180000)
 		return 1;