PCI: dwc: ep: Mirror the max link width and speed fields to all functions

PCI: dwc: ep: Mirror the max link width and speed fields to all functions

PCIe r7.0, section 7.5.3.6 states that for multi-function devices, the
Max Link Width and Max Link Speed fields in the Link Capabilities
Register must report the same values for all functions.

Currently, dw_pcie_setup() programs these fields only for Function 0
via dw_pcie_link_set_max_speed() and dw_pcie_link_set_max_link_width().
For multi-function endpoint configurations, Function 1 and beyond retain
their default values, violating the PCIe specification.

Fix this by reading the Max Link Width and Max Link Speed fields from
Link Capabilities Register of Function 0 after dw_pcie_setup() completes,
then mirroring these values to all other functions.

Fixes: 24ede430fa49 ("PCI: designware-ep: Add multiple PFs support for DWC")
Fixes: 89db0793c9f2 ("PCI: dwc: Add missing PCI_EXP_LNKCAP_MLW handling")
Signed-off-by: Aksh Garg <a-garg7@ti.com>
[mani: renamed ref_lnkcap to func0_lnkcap]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Link: https://patch.msgid.link/20260224083817.916782-3-a-garg7@ti.com