drm/i915: Drop checks for max_pixclk failures in cdclk computation

commit 565602d7501a ("drm/i915: Do not acquire crtc state to check clock during modeset, v4.")
removed the possibility that intel_mode_max_pixclk() or
ilk_max_pixel_rate() might return an error, so let's get rid of the
error checks in the callers as well.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1462995892-32416-2-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -5953,9 +5953,6 @@ static int valleyview_modeset_calc_cdclk(struct drm_atomic_state *state)
 	struct intel_atomic_state *intel_state =
 		to_intel_atomic_state(state);
 
-	if (max_pixclk < 0)
-		return max_pixclk;
-
 	intel_state->cdclk = intel_state->dev_cdclk =
 		valleyview_calc_cdclk(dev_priv, max_pixclk);
 
@@ -5973,9 +5970,6 @@ static int broxton_modeset_calc_cdclk(struct drm_atomic_state *state)
 	struct intel_atomic_state *intel_state =
 		to_intel_atomic_state(state);
 
-	if (max_pixclk < 0)
-		return max_pixclk;
-
 	intel_state->cdclk = intel_state->dev_cdclk =
 		broxton_calc_cdclk(dev_priv, max_pixclk);