mfd: sprd: Remove unnecessary spi_bus_type setting

The spi_register_driver() will set the spi_bus_type for the spi_driver,
thus remove the redundant setting in this driver.
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/sprd-sc27xx-spi.c

@@ -284,7 +284,6 @@ MODULE_DEVICE_TABLE(of, sprd_pmic_match);
 static struct spi_driver sprd_pmic_driver = {
 	.driver = {
 		.name = "sc27xx-pmic",
-		.bus = &spi_bus_type,
 		.of_match_table = sprd_pmic_match,
 	},
 	.probe = sprd_pmic_probe,