dma: sh: Don't use ENODEV for failing slave lookup

If dmaengine driver's .device_alloc_chan_resources() method returns -ENODEV,
dma_request_channel() will decide, that the driver has been removed and will
remove the device from its list. To prevent this use ENXIO if a slave lookup
fails.

Reported-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: stable@vger.kernel.org
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>