skd: fix unchecked return values

Check return values of dma_set_mask_and_coherent().

Otherwise, if dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
fails, the following piece of code will be executed even when the call
to dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32)); returns 0:

dev_err(&pdev->dev, "DMA mask error %d\n", rc);
goto err_out_regions;

Addresses-Coverity-ID: 1474553 ("Unchecked return value")
Fixes: 13812621 ("skd: switch to the generic DMA API")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>