drm/i915: Extract a intel_power_well_disable() function

Similar to the ->enable vfunc in patch "drm/i915: Extract a
intel_power_well_enable() function".

v2 (from Paulo):
  - Same s/i915_/intel_/ bikeshed as the previous patch.
  - Update the commit hash.
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -76,6 +76,14 @@ static void intel_power_well_enable(struct drm_i915_private *dev_priv,
 	power_well->hw_enabled = true;
 }
 
+static void intel_power_well_disable(struct drm_i915_private *dev_priv,
+				     struct i915_power_well *power_well)
+{
+	DRM_DEBUG_KMS("disabling %s\n", power_well->name);
+	power_well->hw_enabled = false;
+	power_well->ops->disable(dev_priv, power_well);
+}
+
 /*
  * We should only use the power well if we explicitly asked the hardware to
  * enable it, so check if it's enabled and also check if we've requested it to
@@ -1147,11 +1155,8 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
 	for_each_power_well_rev(i, power_well, BIT(domain), power_domains) {
 		WARN_ON(!power_well->count);
 
-		if (!--power_well->count && i915.disable_power_well) {
-			DRM_DEBUG_KMS("disabling %s\n", power_well->name);
-			power_well->hw_enabled = false;
-			power_well->ops->disable(dev_priv, power_well);
-		}
+		if (!--power_well->count && i915.disable_power_well)
+			intel_power_well_disable(dev_priv, power_well);
 	}
 
 	mutex_unlock(&power_domains->lock);