soc/amd/common: Scan bridge devices behind SoCs GPU Controller

Scan devices behind SoCs GPU controller to expose more buses.

BUG=b:204401306
BRANCH=guybrush
TEST=emerge-guybrush coreboot

Change-Id: Ib78e6570f101c71efaf9cc1843defcb05301cd30
Signed-off-by: Kevin Chiu <kevin.chiu.17802@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61860
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>

src/soc/amd/common/block/graphics/graphics.c

@@ -173,6 +173,7 @@ static const struct device_operations graphics_ops = {
 	.set_resources		= graphics_set_resources,
 	.enable_resources	= pci_dev_enable_resources,
 	.init			= graphics_dev_init,
+	.scan_bus               = scan_static_bus,
 	.ops_pci		= &pci_dev_ops_pci,
 	.write_acpi_tables	= pci_rom_write_acpi_tables,
 	.acpi_fill_ssdt		= graphics_fill_ssdt,