spi/mpc83xx: fix NULL pdata dereference bug

Commit 178db7d, "spi: Fix device unregistration when unregistering
the bus master", changed device initialization to be children of the
bus master, not children of the bus masters parent device. The pdata
pointer used in fsl_spi_chipselect must updated to reflect the changed
initialization.

Signed-off-by: Kenth Eriksson <kenth.eriksson@transmode.com>
Acked-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/spi/spi-fsl-spi.c

@@ -139,10 +139,12 @@ static void fsl_spi_change_mode(struct spi_device *spi)
 static void fsl_spi_chipselect(struct spi_device *spi, int value)
 {
 	struct mpc8xxx_spi *mpc8xxx_spi = spi_master_get_devdata(spi->master);
-	struct fsl_spi_platform_data *pdata = spi->dev.parent->platform_data;
+	struct fsl_spi_platform_data *pdata;
 	bool pol = spi->mode & SPI_CS_HIGH;
 	struct spi_mpc8xxx_cs	*cs = spi->controller_state;
 
+	pdata = spi->dev.parent->parent->platform_data;
+
 	if (value == BITBANG_CS_INACTIVE) {
 		if (pdata->cs_control)
 			pdata->cs_control(spi, !pol);