This is a preparation before adding the Msg-type outbound iATU
mapping. The respective update will require two more arguments added
to __dw_pcie_prog_outbound_atu(). That will make the already
complicated function prototype even more hard to comprehend accepting
_eight_ arguments.

To prevent that and keep the code more-or-less readable, move all the
outbound iATU-related arguments to a new config structure: struct
dw_pcie_ob_atu_cfg, and pass a pointer to dw_pcie_prog_outbound_atu(). The
structure should be locally defined and populated with the outbound iATU
settings implied by the caller context.

As a result of this change there is no longer need in having the two
distinctive methods for the Host and Endpoint outbound iATU setups since
the code can directly call the dw_pcie_prog_outbound_atu() method with the
config structure populated, so drop dw_pcie_prog_ep_outbound_atu().

[kwilczynski: commit log]
Link: https://lore.kernel.org/linux-pci/20240418-pme_msg-v8-2-a54265c39742@nxp.comSigned-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>