dt-bindings: PCI: rcar: Add bindings for R-Car PCIe endpoint controller

This patch adds the bindings for the R-Car PCIe endpoint driver.

Link: https://lore.kernel.org/r/1588854799-13710-7-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com


Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>