spi: core: Propagate error code of add_uevent_var()

add_uevent_var() can fail, let caller know about this.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi.c

@@ -321,8 +321,7 @@ static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
 	if (rc != -ENODEV)
 		return rc;
 
-	add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
-	return 0;
+	return add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
 }
 
 struct bus_type spi_bus_type = {