drm: vmwgfx: remove drm_driver::master_set() return type

The function always returns zero (success). Ideally we'll remove it all
together - although that's requires a little more work.

For now, we can drop the return type and simplify the drm core code
surrounding it.

v2: remove redundant assignment (Sam)

Cc: David Airlie <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: VMware Graphics <[e-mail]>
Cc: Roland Scheidegger <[e-mail]>
Signed-off-by: Emil Velikov <[e-mail]>
Cc: Sam Ravnborg <[e-mail]>
Reviewed-by: Sam Ravnborg <[e-mail]>
Reviewed-by: Roland Scheidegger <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/drm_auth.c

···
 	return master;
 }
 
-static int drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
-			  bool new_master)
+static void drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
+			   bool new_master)
 {
-	int ret = 0;
-
 	dev->master = drm_master_get(fpriv->master);
-	if (dev->driver->master_set) {
-		ret = dev->driver->master_set(dev, fpriv, new_master);
-		if (unlikely(ret != 0)) {
-			drm_master_put(&dev->master);
-		}
-	}
+	if (dev->driver->master_set)
+		dev->driver->master_set(dev, fpriv, new_master);
 
-	fpriv->was_master = (ret == 0);
-	return ret;
+	fpriv->was_master = true;
 }
 
 static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
 {
 	struct drm_master *old_master;
-	int ret;
 
 	lockdep_assert_held_once(&dev->master_mutex);
 
···
 	fpriv->is_master = 1;
 	fpriv->authenticated = 1;
 
-	ret = drm_set_master(dev, fpriv, true);
-	if (ret)
-		goto out_err;
+	drm_set_master(dev, fpriv, true);
 
 	if (old_master)
 		drm_master_put(&old_master);
 
 	return 0;
-
-out_err:
-	/* drop references and restore old master on failure */
-	drm_master_put(&fpriv->master);
-	fpriv->master = old_master;
-	fpriv->is_master = 0;
-
-	return ret;
 }
 
 /*
···
 		goto out_unlock;
 	}
 
-	ret = drm_set_master(dev, file_priv, false);
+	drm_set_master(dev, file_priv, false);
 out_unlock:
 	mutex_unlock(&dev->master_mutex);
 	return ret;

drivers/gpu/drm/vmwgfx/vmwgfx_drv.c

···
 }
 #endif
 
-static int vmw_master_set(struct drm_device *dev,
-			  struct drm_file *file_priv,
-			  bool from_open)
+static void vmw_master_set(struct drm_device *dev,
+			   struct drm_file *file_priv,
+			   bool from_open)
 {
 	/*
 	 * Inform a new master that the layout may have changed while
···
 	 */
 	if (!from_open)
 		drm_sysfs_hotplug_event(dev);
-
-	return 0;
 }
 
 static void vmw_master_drop(struct drm_device *dev,

include/drm/drm_drv.h

···
 	 *
 	 * Called whenever the minor master is set. Only used by vmwgfx.
 	 */
-	int (*master_set)(struct drm_device *dev, struct drm_file *file_priv,
-			  bool from_open);
+	void (*master_set)(struct drm_device *dev, struct drm_file *file_priv,
+			   bool from_open);
 	/**
 	 * @master_drop:
 	 *