drm/i915: fix lookup_power_well for power wells without any domain

The current lookup code wouldn't find a power well if it's not in any
power domain. There wasn't any power wells before but an upcoming patch
will detach the power domains from power well#1 and the MISC IO power
wells, so fix things up accordingly.
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NPatrik Jakobsson <patrik.jakobsson@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1446657859-9598-3-git-send-email-imre.deak@intel.com

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -961,10 +961,12 @@ static struct i915_power_well *lookup_power_well(struct drm_i915_private *dev_pr
 						 int power_well_id)
 {
 	struct i915_power_domains *power_domains = &dev_priv->power_domains;
-	struct i915_power_well *power_well;
 	int i;
 
-	for_each_power_well(i, power_well, POWER_DOMAIN_MASK, power_domains) {
+	for (i = 0; i < power_domains->power_well_count; i++) {
+		struct i915_power_well *power_well;
+
+		power_well = &power_domains->power_wells[i];
 		if (power_well->data == power_well_id)
 			return power_well;
 	}