PCI/pwrctrl: Create pwrctrl device if graph port is found

PCI/pwrctrl: Create pwrctrl device if graph port is found

The devicetree node of the PCIe Root Port/Slot could have the graph port to
link the PCIe M.2 connector node. Since the M.2 connectors are modeled as
Power Sequencing devices, they need to be controlled by the pwrctrl driver
like the Root Port/Slot supplies.

Hence, create the pwrctrl device if the graph port is found in the node.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://patch.msgid.link/20260128-pci-m2-v7-2-9b3a5fe3d244@oss.qualcomm.com