mfd: mc13xxx: Add missing spi_setup()

The probe routine should call spi_setup() to configure the SPI bus
so it can properly communicate with the device.

Signed-off-by: Alexander Shiyan <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/mfd/mc13xxx-spi.c

···
 	mc13xxx->irq = spi->irq;
 
 	spi->max_speed_hz = spi->max_speed_hz ? : 26000000;
+	ret = spi_setup(spi);
+	if (ret)
+		return ret;
 
 	mc13xxx->regmap = devm_regmap_init(&spi->dev, &regmap_mc13xxx_bus,
 					   &spi->dev,