can: mcp251x: Remove redundant spi driver bus initialization

In ancient times it was necessary to manually initialize the bus field of an
spi_driver to spi_bus_type. These days this is done in spi_driver_register() so
we can drop the manual assignment.

The patch was generated using the following coccinelle semantic patch:
// <smpl>
@@
identifier _driver;
@@
struct spi_driver _driver = {
	.driver = {
-		.bus = &spi_bus_type,
	},
};
// </smpl>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/mcp251x.c

@@ -1207,7 +1207,6 @@ MODULE_DEVICE_TABLE(spi, mcp251x_id_table);
 static struct spi_driver mcp251x_can_driver = {
 	.driver = {
 		.name = DEVICE_NAME,
-		.bus = &spi_bus_type,
 		.owner = THIS_MODULE,
 	},