of_dma_request_slave_channel should return either pointer for valid
dma_chan or ERR_PTR() error code, NULL is not expected to be returned.
Signed-off-by: NPeter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>