drm/i915: Fix lock dropping in intel_tv_detect()

When intel_tv_detect() fails to do load detection it would forget to
drop the locks and clean up the acquire context. Fix it up.

This is a regression from:
 commit 208bf9fdcd3575aa4a5d48b3e0295f7cdaf6fc44
 Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
 Date:   Mon Aug 11 13:15:35 2014 +0300

    drm/i915: Fix locking for intel_enable_pipe_a()

v2: Make the code more readable (Chris)
v3: Drop WARN_ON(type < 0) (Chris)

Cc: stable@vger.kernel.org
Cc: Tibor Billes <tbilles@gmx.com>
Reported-by: Tibor Billes <tbilles@gmx.com>
Tested-by: Tibor Billes <tbilles@gmx.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_tv.c

@@ -1311,6 +1311,7 @@ intel_tv_detect(struct drm_connector *connector, bool force)
 {
 	struct drm_display_mode mode;
 	struct intel_tv *intel_tv = intel_attached_tv(connector);
+	enum drm_connector_status status;
 	int type;
 
 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s] force=%d\n",
@@ -1328,16 +1329,19 @@ intel_tv_detect(struct drm_connector *connector, bool force)
 		if (intel_get_load_detect_pipe(connector, &mode, &tmp, &ctx)) {
 			type = intel_tv_detect_type(intel_tv, connector);
 			intel_release_load_detect_pipe(connector, &tmp);
+			status = type < 0 ?
+				connector_status_disconnected :
+				connector_status_connected;
 		} else
-			return connector_status_unknown;
+			status = connector_status_unknown;
 
 		drm_modeset_drop_locks(&ctx);
 		drm_modeset_acquire_fini(&ctx);
 	} else
 		return connector->status;
 
-	if (type < 0)
-		return connector_status_disconnected;
+	if (status != connector_status_connected)
+		return status;
 
 	intel_tv->type = type;
 	intel_tv_find_better_format(connector);