Merge branch 'pci/pwrctrl'

Merge branch 'pci/pwrctrl'

- Create pwrctrl devices in pci_scan_device() to make it more symmetric
  with pci_pwrctrl_unregister() and make pwrctrl devices for PCI bridges
  possible (Manivannan Sadhasivam)

- Unregister pwrctrl devices in pci_destroy_dev() so DOE, ASPM, etc. can
  still access devices after pci_stop_dev() (Manivannan Sadhasivam)

- If there's a pwrctrl device for a PCI device, skip scanning it because
  the pwrctrl core will rescan the bus after the device is powered on
  (Manivannan Sadhasivam)

- Add a pwrctrl driver for PCI slots based on voltage regulators described
  via devicetree (Manivannan Sadhasivam)

* pci/pwrctrl:
  PCI/pwrctrl: Add pwrctrl driver for PCI slots
  dt-bindings: vendor-prefixes: Document the 'pciclass' prefix
  PCI/pwrctrl: Skip scanning for the device further if pwrctrl device is created
  PCI/pwrctrl: Move pci_pwrctrl_unregister() to pci_destroy_dev()
  PCI/pwrctrl: Move creation of pwrctrl devices to pci_scan_device()