kaweth: remove ifdefed out call to dma_supported

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>