powerpc/eeh: Use dev_driver_string() instead of struct pci_dev->driver->name

Replace pdev->driver->name by dev_driver_string() for the corresponding
struct device.  This is a step toward removing pci_dev->driver.

Move the function nearer its only user and instead of the ?: operator use a
normal "if" which is more readable.

Link: https://lore.kernel.org/r/20211004125935.2300113-6-u.kleine-koenig@pengutronix.deSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

arch/powerpc/include/asm/ppc-pci.h

@@ -55,11 +55,6 @@ void eeh_pe_dev_mode_mark(struct eeh_pe *pe, int mode);
 void eeh_sysfs_add_device(struct pci_dev *pdev);
 void eeh_sysfs_remove_device(struct pci_dev *pdev);
 
-static inline const char *eeh_driver_name(struct pci_dev *pdev)
-{
-	return (pdev && pdev->driver) ? pdev->driver->name : "<null>";
-}
-
 #endif /* CONFIG_EEH */
 
 #define PCI_BUSNO(bdfn) ((bdfn >> 8) & 0xff)

arch/powerpc/kernel/eeh.c

@@ -399,6 +399,14 @@ static int eeh_phb_check_failure(struct eeh_pe *pe)
 	return ret;
 }
 
+static inline const char *eeh_driver_name(struct pci_dev *pdev)
+{
+	if (pdev)
+		return dev_driver_string(&pdev->dev);
+
+	return "<null>";
+}
+
 /**
  * eeh_dev_check_failure - Check if all 1's data is due to EEH slot freeze
  * @edev: eeh device