at_hdmac: bugfix for enabling channel irq

commit 463894705e4089d0ff69e7d877312d496ac70e5b deleted redundant
chan_id and chancnt initialization in dma drivers as this is done
in dma_async_device_register().

However, atc_enable_irq() relied on chan_id set before registering
the device, what left only channel 0 functional for this driver.

This patch introduces atc_enable/disable_chan_irq() as a variant
of atc_enable/disable_irq() with the channel as explicit argument.

Signed-off-by: Nikolaus Voss <n.voss@weinmann.de>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 97f87b2..f4aed5f 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -1343,7 +1343,7 @@
 
 		tasklet_init(&atchan->tasklet, atc_tasklet,
 				(unsigned long)atchan);
-		atc_enable_irq(atchan);
+		atc_enable_chan_irq(atdma, i);
 	}
 
 	/* set base routines */
@@ -1410,7 +1410,7 @@
 		struct at_dma_chan	*atchan = to_at_dma_chan(chan);
 
 		/* Disable interrupts */
-		atc_disable_irq(atchan);
+		atc_disable_chan_irq(atdma, chan->chan_id);
 		tasklet_disable(&atchan->tasklet);
 
 		tasklet_kill(&atchan->tasklet);