fsldma: check for NO_IRQ in fsl_dma_chan_remove()

There's no per-channel IRQ on mpc83xx, so only call free_irq if we have one.
Acked-by: NTimur Tabi <timur@freescale.com>
Acked-by: NLi Yang <leoli@freescale.com>
Signed-off-by: NPeter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

drivers/dma/fsldma.c

@@ -890,7 +890,8 @@ err_no_reg:
 
 static void fsl_dma_chan_remove(struct fsl_dma_chan *fchan)
 {
-	free_irq(fchan->irq, fchan);
+	if (fchan->irq != NO_IRQ)
+		free_irq(fchan->irq, fchan);
 	list_del(&fchan->common.device_node);
 	iounmap(fchan->reg_base);
 	kfree(fchan);