PCI: dwc: Update pci->num_lanes to maximum supported link width

PCI: dwc: Update pci->num_lanes to maximum supported link width

If the num-lanes property is not present in the devicetree, update
pci->num_lanes with the hardware supported maximum link width using
the newly introduced dw_pcie_link_get_max_link_width() API.

The API is used to get the Maximum Link Width (MLW) of the controller.

Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
[mani: reworded commit message a bit]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://patch.msgid.link/20250328-preset_v6-v9-3-22cfa0490518@oss.qualcomm.com