atm: firestream: check the return value of ioremap() in fs_init()

The function ioremap() in fs_init() can fail, so its return value should
be checked.
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/atm/firestream.c

@@ -1676,6 +1676,8 @@ static int fs_init(struct fs_dev *dev)
 	dev->hw_base = pci_resource_start(pci_dev, 0);
 
 	dev->base = ioremap(dev->hw_base, 0x1000);
+	if (!dev->base)
+		return 1;
 
 	reset_chip (dev);