[3/4] I/OAT: fix async_tx.callback checking

async_tx.callback should be checked for the first
not the last descriptor in the chain.

Cc: <[e-mail]>
Signed-off-by: Maciej Sosnowski <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/dma/ioat_dma.c

···
 	}
 
 	hw->ctl = IOAT_DMA_DESCRIPTOR_CTL_CP_STS;
-	if (new->async_tx.callback) {
+	if (first->async_tx.callback) {
 		hw->ctl |= IOAT_DMA_DESCRIPTOR_CTL_INT_GN;
 		if (first != new) {
 			/* move callback into to last desc */
···
 	}
 
 	hw->ctl |= IOAT_DMA_DESCRIPTOR_CTL_CP_STS;
-	if (new->async_tx.callback) {
+	if (first->async_tx.callback) {
 		hw->ctl |= IOAT_DMA_DESCRIPTOR_CTL_INT_GN;
 		if (first != new) {
 			/* move callback into to last desc */