PCI: dwc: Rename .func_conf_select to .get_dbi_offset in struct dw_pcie_ep_ops

Since the struct member .func_conf_select makes the intentions behind it
difficult to ascertain from its name alone, rename it to .get_dbi_offset
to make the intended usage more obvious.

[kwilczynski: commmit log]
Suggested-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/linux-pci/20231220053829.1921187-4-yoshihiro.shimoda.uh@renesas.com


Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>