dmaengine: dw: properly read DWC_PARAMS register

commit 6bea0f6d upstream.

In case we have less than maximum allowed channels (8) and autoconfiguration is
enabled the DWC_PARAMS read is wrong because it uses different arithmetic to
what is needed for channel priority setup.

Re-do the caclulations properly. This now works on AVR32 board well.

Fixes: fed2574b (dw_dmac: introduce software emulation of LLP transfers)
Cc: yitian.bu@tangramtek.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/dma/dw/core.c

@@ -1573,7 +1573,6 @@ int dw_dma_probe(struct dw_dma_chip *chip, struct dw_dma_platform_data *pdata)
 	INIT_LIST_HEAD(&dw->dma.channels);
 	for (i = 0; i < nr_channels; i++) {
 		struct dw_dma_chan	*dwc = &dw->chan[i];
-		int			r = nr_channels - i - 1;
 
 		dwc->chan.device = &dw->dma;
 		dma_cookie_init(&dwc->chan);
@@ -1585,7 +1584,7 @@ int dw_dma_probe(struct dw_dma_chip *chip, struct dw_dma_platform_data *pdata)
 
 		/* 7 is highest priority & 0 is lowest. */
 		if (pdata->chan_priority == CHAN_PRIORITY_ASCENDING)
-			dwc->priority = r;
+			dwc->priority = nr_channels - i - 1;
 		else
 			dwc->priority = i;
 
@@ -1605,6 +1604,7 @@ int dw_dma_probe(struct dw_dma_chip *chip, struct dw_dma_platform_data *pdata)
 		/* Hardware configuration */
 		if (autocfg) {
 			unsigned int dwc_params;
+			unsigned int r = DW_DMA_MAX_NR_CHANNELS - i - 1;
 			void __iomem *addr = chip->regs + r * sizeof(u32);
 
 			dwc_params = dma_read_byaddr(addr, DWC_PARAMS);