dw-dma: Fix channel status

At the end of the DMA, we need to set the channel status into
parapre, otherwise next dma start will fail.
This will fix APL pause resume issues.

Signed-off-by: Pan Xiuli <xiuli.pan@linux.intel.com>

--
Test with:
Mininow max rt5651 and GP-MRB nocodec
SOF master: 728f1ff3e3
SOF-Tool master: 5b5bbe31e6
https://github.com/plbossart/sound/tree/topic/sof-v4.14:
fe5e29155127a717ba5ae454b4bdde99afa67723

src/drivers/dw-dma.c

@@ -953,6 +953,7 @@ static void dw_dma_irq_handler(void *data)
 				trace_dma("LSo");
 				/* disable channel, finished */
 				dw_write(dma, DW_DMA_CHAN_EN, CHAN_DISABLE(i));
+				p->chan[i].status = COMP_STATE_PREPARE;
 			}
 		}
 #endif