Otherwise we get a warning in case of CONFIG_DMA_API_DEBUG=y

[   45.775943] WARNING: at lib/dma-debug.c:933 check_unmap+0x5d6/0x6ac()
[   45.782369] dw_dmac dw_dmac.0: DMA-API: device driver failed to check map error[device address=0x00000000356efcc0] [size=28 bytes] [mapped as single]
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>