PCI: rzg3s-host: Explicitly set class code for RZ/G3E compatibility

PCI: rzg3s-host: Explicitly set class code for RZ/G3E compatibility

Program the class code register explicitly during PCIe configuration
initialization. RZ/G3E requires this register to be set, while RZ/G3S
has these values as hardware defaults.

This configuration is harmless for RZ/G3S where these match the hardware
defaults, and necessary for RZ/G3E to properly identify the device as a
PCI bridge.

Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> # RZ/V2N EVK
Tested-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Link: https://patch.msgid.link/20260306143423.19562-11-john.madieu.xa@bp.renesas.com