misc: cb710: Fix a NULL vs IS_ERR() check in probe()

The pcim_iomap_region() function never returns NULL, it returns error
pointers.  Update the checking to match.

Fixes: b91c135 ("misc: cb710: Replace deprecated PCI functions")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/aQITFDPyuzjNN4GN@stanley.mountain
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Dan Carpenter

drivers/misc/cb710/core.c

@@ -226,8 +226,8 @@ static int cb710_probe(struct pci_dev *pdev,
 	spin_lock_init(&chip->irq_lock);
 	chip->pdev = pdev;
 	chip->iobase = pcim_iomap_region(pdev, 0, KBUILD_MODNAME);
-	if (!chip->iobase)
-		return -ENOMEM;
+	if (IS_ERR(chip->iobase))
+		return PTR_ERR(chip->iobase);
 
 	pci_set_drvdata(pdev, chip);