drm/auth: make drm_{set,drop}master_ioctl symmetrical

Currently the ret handling is all over the place - with two redundant
assignments and another one addressed earlier.

Use the exact same flow in both functions.

v2: straighten the code flow, instead of just removing the assignments

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

drivers/gpu/drm/drm_auth.c

···
 int drm_setmaster_ioctl(struct drm_device *dev, void *data,
 			struct drm_file *file_priv)
 {
-	int ret = 0;
+	int ret;
 
 	mutex_lock(&dev->master_mutex);
 
···
 	if (ret)
 		goto out_unlock;
 
-	ret = -EINVAL;
-	if (!drm_is_current_master(file_priv))
+	if (!drm_is_current_master(file_priv)) {
+		ret = -EINVAL;
 		goto out_unlock;
+	}
 
-	if (!dev->master)
+	if (!dev->master) {
+		ret = -EINVAL;
 		goto out_unlock;
+	}
 
 	if (file_priv->master->lessor != NULL) {
 		DRM_DEBUG_LEASE("Attempt to drop lessee %d as master\n", file_priv->master->lessee_id);
···
 		goto out_unlock;
 	}
 
-	ret = 0;
 	drm_drop_master(dev, file_priv);
 out_unlock:
 	mutex_unlock(&dev->master_mutex);