mmc: atmel-mci: restore dma on AVR32

Commit ecb89f2f5f ("mmc: atmel-mci: remove compat for non DT board
when requesting dma chan") broke dma on AVR32 and any other boards not
using DT.  This restores a fallback mechanism for such cases.

Signed-off-by: Mans Rullgard <mans@mansr.com>
Acked-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Acked-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/atmel-mci.c

@@ -2280,6 +2280,23 @@ static int atmci_configure_dma(struct atmel_mci *host)
 {
 	host->dma.chan = dma_request_slave_channel_reason(&host->pdev->dev,
 							"rxtx");
+
+	if (PTR_ERR(host->dma.chan) == -ENODEV) {
+		struct mci_platform_data *pdata = host->pdev->dev.platform_data;
+		dma_cap_mask_t mask;
+
+		if (!pdata->dma_filter)
+			return -ENODEV;
+
+		dma_cap_zero(mask);
+		dma_cap_set(DMA_SLAVE, mask);
+
+		host->dma.chan = dma_request_channel(mask, pdata->dma_filter,
+						     pdata->dma_slave);
+		if (!host->dma.chan)
+			host->dma.chan = ERR_PTR(-ENODEV);
+	}
+
 	if (IS_ERR(host->dma.chan))
 		return PTR_ERR(host->dma.chan);