spi: topcliff-pch: don't hardcode PCI slot to get DMA device

The DMA is a function 0 of the multifunction device where SPI host is attached.
Thus, we may avoid to hardcode PCI slot number.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-topcliff-pch.c

@@ -874,8 +874,8 @@ static void pch_spi_request_dma(struct pch_spi_data *data, int bpw)
 	dma_cap_set(DMA_SLAVE, mask);
 
 	/* Get DMA's dev information */
-	dma_dev = pci_get_bus_and_slot(data->board_dat->pdev->bus->number,
-				       PCI_DEVFN(12, 0));
+	dma_dev = pci_get_slot(data->board_dat->pdev->bus,
+			PCI_DEVFN(PCI_SLOT(data->board_dat->pdev->devfn), 0));
 
 	/* Set Tx DMA */
 	param = &dma->param_tx;