dma_chan_get uses a rather interesting error handling and code path.

Change it to something more usual in the kernel.
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>