dmaengine: coh901318: use NULL for pointer initialization

Sparse complains:
drivers/dma/coh901318_lli.c:78:31: warning: Using plain integer as NULL pointer
drivers/dma/coh901318_lli.c:91:39: warning: Using plain integer as NULL pointer

Use NULL for pointer initialization rather than plain integer
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/coh901318_lli.c

@@ -75,7 +75,7 @@ coh901318_lli_alloc(struct coh901318_pool *pool, unsigned int len)
 	lli = head;
 	lli->phy_this = phy;
 	lli->link_addr = 0x00000000;
-	lli->virt_link_addr = 0x00000000U;
+	lli->virt_link_addr = NULL;
 
 	for (i = 1; i < len; i++) {
 		lli_prev = lli;
@@ -88,7 +88,7 @@ coh901318_lli_alloc(struct coh901318_pool *pool, unsigned int len)
 		DEBUGFS_POOL_COUNTER_ADD(pool, 1);
 		lli->phy_this = phy;
 		lli->link_addr = 0x00000000;
-		lli->virt_link_addr = 0x00000000U;
+		lli->virt_link_addr = NULL;
 
 		lli_prev->link_addr = phy;
 		lli_prev->virt_link_addr = lli;