drm/i915/chv: Fix error path in GPU freq helpers

Atm we wouldn't catch these errors or on the error path we would end up
with a division-by-zero, fix this up.
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NDavid Weinehall <david.weinehall@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1454071949-24677-2-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/intel_pm.c

@@ -7185,9 +7185,10 @@ static int chv_gpu_freq(struct drm_i915_private *dev_priv, int val)
 {
 	int div, czclk_freq = DIV_ROUND_CLOSEST(dev_priv->czclk_freq, 1000);
 
-	div = vlv_gpu_freq_div(czclk_freq) / 2;
+	div = vlv_gpu_freq_div(czclk_freq);
 	if (div < 0)
 		return div;
+	div /= 2;
 
 	return DIV_ROUND_CLOSEST(czclk_freq * val, 2 * div) / 2;
 }
@@ -7196,9 +7197,10 @@ static int chv_freq_opcode(struct drm_i915_private *dev_priv, int val)
 {
 	int mul, czclk_freq = DIV_ROUND_CLOSEST(dev_priv->czclk_freq, 1000);
 
-	mul = vlv_gpu_freq_div(czclk_freq) / 2;
+	mul = vlv_gpu_freq_div(czclk_freq);
 	if (mul < 0)
 		return mul;
+	mul /= 2;
 
 	/* CHV needs even values */
 	return DIV_ROUND_CLOSEST(val * 2 * mul, czclk_freq) * 2;