PCI: Add Rockchip Vendor ID

Move PCI_VENDOR_ID_ROCKCHIP from pci_endpoint_test.c to pci_ids.h and
reuse it in pcie-rockchip-host.c.

Link: https://lore.kernel.org/r/20250218092120.2322784-2-cassel@kernel.org


Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>