[ARM] omap: fix lots of 'Using plain integer as NULL pointer'

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/plat-omap/dma.c b/arch/arm/plat-omap/dma.c
index b4057e2..50f8b4a 100644
--- a/arch/arm/plat-omap/dma.c
+++ b/arch/arm/plat-omap/dma.c
@@ -1233,7 +1233,7 @@
 	/* request and reserve DMA channels for the chain */
 	for (i = 0; i < no_of_chans; i++) {
 		err = omap_request_dma(dev_id, dev_name,
-					callback, 0, &channels[i]);
+					callback, NULL, &channels[i]);
 		if (err < 0) {
 			int j;
 			for (j = 0; j < i; j++)