sparse pointer use of zero as null

Get rid of sparse related warnings from places that use integer as NULL
pointer.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Ian Kent <raven@themaw.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 026439e..c750105 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -882,7 +882,7 @@
 	/* Filter out DMA modes if the device has been configured by
 	   the BIOS as PIO only */
 
-	if (adev->link->ap->ioaddr.bmdma_addr == 0)
+	if (adev->link->ap->ioaddr.bmdma_addr == NULL)
 		xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
 	return xfer_mask;
 }
diff --git a/drivers/base/dmapool.c b/drivers/base/dmapool.c
index fbae867..5beddc3 100644
--- a/drivers/base/dmapool.c
+++ b/drivers/base/dmapool.c
@@ -366,7 +366,7 @@
 	unsigned long		flags;
 	int			map, block;
 
-	if ((page = pool_find_page (pool, dma)) == 0) {
+	if ((page = pool_find_page(pool, dma)) == NULL) {
 		if (pool->dev)
 			dev_err(pool->dev, "dma_pool_free %s, %p/%lx (bad dma)\n",
 				pool->name, vaddr, (unsigned long) dma);
diff --git a/drivers/char/random.c b/drivers/char/random.c
index af274e5..1756b1f 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -649,7 +649,7 @@
 
 void add_interrupt_randomness(int irq)
 {
-	if (irq >= NR_IRQS || irq_timer_state[irq] == 0)
+	if (irq >= NR_IRQS || irq_timer_state[irq] == NULL)
 		return;
 
 	DEBUG_ENT("irq event %d\n", irq);