pch_phub: fix sparse warning

sparse warns about using 0 as NULL pointer,

drivers/misc/pch_phub.c:702:44: warning: Using plain integer as NULL pointer

Signed-off-by: Devendra Naga <develkernel412222@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/misc/pch_phub.c b/drivers/misc/pch_phub.c
index 9fbcacd..e2c066e 100644
--- a/drivers/misc/pch_phub.c
+++ b/drivers/misc/pch_phub.c
@@ -699,7 +699,7 @@
 	chip->pch_phub_base_address = pci_iomap(pdev, 1, 0);
 
 
-	if (chip->pch_phub_base_address == 0) {
+	if (chip->pch_phub_base_address == NULL) {
 		dev_err(&pdev->dev, "%s : pci_iomap FAILED", __func__);
 		ret = -ENOMEM;
 		goto err_pci_iomap;