arm64: dts: renesas: r8a779g0: Describe PCIe root ports

arm64: dts: renesas: r8a779g0: Describe PCIe root ports

Add nodes which describe the root ports in the PCIe controller DT nodes.
This can be used together with the pwrctrl driver to control clock and
power supply to a PCIe slot.  For example usage, refer to the Sparrow
Hawk board.

Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Link: https://lore.kernel.org/20250607194541.79176-2-marek.vasut+renesas@mailbox.org
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>