Merge branch 'pci/controller/imx6'

- Add i.MX8MM, i.MX8MQ, i.MX8MP endpoint mode DT binding and driver support
  (Richard Zhu)

* pci/controller/imx6:
  PCI: imx6: Add i.MX8MP PCIe EP support
  PCI: imx6: Add i.MX8MM PCIe EP support
  PCI: imx6: Add i.MX8MQ PCIe EP support
  PCI: imx6: Add i.MX PCIe EP mode support
  misc: pci_endpoint_test: Add i.MX8 PCIe EP device support
  dt-bindings: imx6q-pcie: Add i.MX8MP PCIe EP mode compatible string
  dt-bindings: imx6q-pcie: Add i.MX8MQ PCIe EP mode compatible string
  dt-bindings: imx6q-pcie: Add i.MX8MM PCIe EP mode compatible string