drm/radeon: simplify if-if to if-else

Replace `if (!ret)` with `else` for simplification.
Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_pm.c

@@ -1629,7 +1629,7 @@ int radeon_pm_late_init(struct radeon_device *rdev)
 			ret = device_create_file(rdev->dev, &dev_attr_power_method);
 			if (ret)
 				DRM_ERROR("failed to create device file for power method\n");
-			if (!ret)
+			else
 				rdev->pm.sysfs_initialized = true;
 		}
 	}