Fix sparse warning: Using plain integer as NULL pointer

This patch fixes the "using plain integer as NULL pointer" warnings
generated by running sparse on the flashrom source.

Corresponding to flashrom svn r1255.

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Acked-by: Mathias Krause <mathias.krause@secunet.com>
Acked-by: Stefan Reinauer <stepan@coreboot.org>
diff --git a/chipset_enable.c b/chipset_enable.c
index 6d6008e..0896bce 100644
--- a/chipset_enable.c
+++ b/chipset_enable.c
@@ -1173,7 +1173,7 @@
 
 int chipset_flash_enable(void)
 {
-	struct pci_dev *dev = 0;
+	struct pci_dev *dev = NULL;
 	int ret = -2;		/* Nothing! */
 	int i;