dmaengine: at_hdmac: implement pause and resume in atc_control

Pause and resume controls are useful for audio devices. This also returns
correct status from atc_tx_status() in case chan is paused.

Idea from dw_dmac patch by Linus Walleij.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
diff --git a/drivers/dma/at_hdmac_regs.h b/drivers/dma/at_hdmac_regs.h
index ae3056d..087dbf1 100644
--- a/drivers/dma/at_hdmac_regs.h
+++ b/drivers/dma/at_hdmac_regs.h
@@ -191,6 +191,7 @@
  */
 enum atc_status {
 	ATC_IS_ERROR = 0,
+	ATC_IS_PAUSED = 1,
 	ATC_IS_CYCLIC = 24,
 };