[PATCH -next] Bluetooth: btmtksdio: use NULL instead of zero

[YueHaibing]

Fix sparse warnings:

drivers/bluetooth/btmtksdio.c:499:57: warning: Using plain integer as NULL 
pointer
drivers/bluetooth/btmtksdio.c:533:57: warning: Using plain integer as NULL 
pointer

Signed-off-by: YueHaibing <yuehaib...@huawei.com>
---
 drivers/bluetooth/btmtksdio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/bluetooth/btmtksdio.c b/drivers/bluetooth/btmtksdio.c
index c7ab7a23bd67..ba45c59bd9f3 100644
--- a/drivers/bluetooth/btmtksdio.c
+++ b/drivers/bluetooth/btmtksdio.c
@@ -496,7 +496,7 @@ static void btmtksdio_interrupt(struct sdio_func *func)
        sdio_claim_host(bdev->func);
 
        /* Disable interrupt */
-       sdio_writel(func, C_INT_EN_CLR, MTK_REG_CHLPCR, 0);
+       sdio_writel(func, C_INT_EN_CLR, MTK_REG_CHLPCR, NULL);
 
        int_status = sdio_readl(func, MTK_REG_CHISR, NULL);
 
@@ -530,7 +530,7 @@ static void btmtksdio_interrupt(struct sdio_func *func)
        }
 
        /* Enable interrupt */
-       sdio_writel(func, C_INT_EN_SET, MTK_REG_CHLPCR, 0);
+       sdio_writel(func, C_INT_EN_SET, MTK_REG_CHLPCR, NULL);
 
        pm_runtime_mark_last_busy(bdev->dev);
        pm_runtime_put_autosuspend(bdev->dev);
-- 
2.17.1