dmaengine: zx: set DMA_CYCLIC cap_mask bit

The zx_dma driver supports cyclic transfer mode.  Let's set DMA_CYCLIC
cap_mask bit to make that clear, and avoid unnecessary failure when
clients request channel via dma_request_chan_by_mask() with DMA_CYCLIC
bit set in mask.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Jun Nie <jun.nie@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>