ssb: Use dev_driver_string() instead of pci_dev->driver->name

ssb: Use dev_driver_string() instead of pci_dev->driver->name

All drivers that use ssb_pcihost_probe(), i.e., b43_pci_bridge_driver and
b44_pci_driver, set the pci_driver.name, and __pci_register_driver() sets
the struct driver.name member to the same value.

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

Link: https://lore.kernel.org/r/20211004125935.2300113-7-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Michael Büsch <m@bues.ch>