dmaengine: shdma: Make channel filter ignore unrelated devices

The shdma_chan_filter() function relies on the DMA channel being
embedded in an shdma_chan structure. If this assumption isn't true, for
instance when the system contains DMA channels supported by an unrelated
driver, the function will crash.

Avoid this by returning false directly when the channel belongs to an
unrelated device.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>