dmaengine: pl330: redefine the cyclic transfer

dmaengine: pl330: redefine the cyclic transfer

dmaengine_prep_dma_cyclic, to use buf_addr with size buf_len,
generate an interrupt every period_len. But DMA must restart
every period_len, it may be blocked. If i2s use it, it may
cause sound break. Infiniteloop is helpful to solve this
issue. In infiniteloop mode, when DMA transfers all buf_len
data, it goes back to the start of buf_addr and continue to
transfer endless.

Change-Id: Ibbc92c416d0a9dd58633e7991176c86300c3da98
Signed-off-by: Huibin Hong <huibin.hong@rock-chips.com>