dmaengine: mxs-dma: Declare slave capabilities for the generic code

Since ecc19d17 ("dmaengine: Add a warning for drivers not using the
generic slave caps retrieval") the following warning is observed:

[    0.113023] ------------[ cut here ]------------
[    0.113053] WARNING: CPU: 0 PID: 1 at drivers/dma/dmaengine.c:830 dma_async_device_register+0x2a0/0x4c8()
[    0.113063] this driver doesn't support generic slave capabilities reporting

Declare the slave capabilities to avoid such warning.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/mxs-dma.c

@@ -848,6 +848,10 @@ static int __init mxs_dma_probe(struct platform_device *pdev)
 	mxs_dma->dma_device.device_pause = mxs_dma_pause_chan;
 	mxs_dma->dma_device.device_resume = mxs_dma_resume_chan;
 	mxs_dma->dma_device.device_terminate_all = mxs_dma_terminate_all;
+	mxs_dma->dma_device.src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+	mxs_dma->dma_device.dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES);
+	mxs_dma->dma_device.directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
+	mxs_dma->dma_device.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
 	mxs_dma->dma_device.device_issue_pending = mxs_dma_enable_chan;
 
 	ret = dma_async_device_register(&mxs_dma->dma_device);