This reverts commit 2a4d9408.

Robert reported a NULL pointer dereference caused by the PCI core
(local_pci_probe()) calling the i2c_designware_pci driver's
.runtime_resume() method before the .probe() method.  i2c_dw_pci_resume()
depends on initialization done by i2c_dw_pci_probe().

Prior to 2a4d9408 ("PCI: Use to_pci_driver() instead of
pci_dev->driver"), pci_pm_runtime_resume() avoided calling the
.runtime_resume() method because pci_dev->driver had not been set yet.

2a4d9408 and b5f9c644 ("PCI: Remove struct pci_dev->driver"),
removed pci_dev->driver, replacing it by device->driver, which *has* been
set by this time, so pci_pm_runtime_resume() called the .runtime_resume()
method when it previously had not.

Fixes: 2a4d9408 ("PCI: Use to_pci_driver() instead of pci_dev->driver")
Link: https://lore.kernel.org/linux-i2c/CAP145pgdrdiMAT7=-iB1DMgA7t_bMqTcJL4N0=6u8kNY3EU0dw@mail.gmail.com/Reported-by: NRobert Święcki <robert@swiecki.net>
Tested-by: NRobert Święcki <robert@swiecki.net>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>