PCI: dwc: endpoint: Introduce .pre_init() and .deinit()

PCI: dwc: endpoint: Introduce .pre_init() and .deinit()

Renesas R-Car Gen4 PCIe controllers require vendor-specific
initialization before .init().

To use dw->dbi and dw->num-lanes in the initialization code,
introduce .pre_init() into struct dw_pcie_ep_ops. While at it,
also introduce .deinit() to disable the controller by using
vendor-specific de-initialization.

Note that the ep_init in the struct dw_pcie_ep_ops should be
renamed to init later.

Link: https://lore.kernel.org/linux-pci/20231018085631.1121289-9-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>