device/pci_ops: Simplify logic for PCI bus ops

Nobody ever sets ops_pci_bus. This implies pci_bus_ops() always
returns pci_bus_default_ops() and get_pbus returns NULL.

Change-Id: Ia30d579e1efe6542dc58714f2e7077507847c0de
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/31684
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/include/device/device.h

@@ -68,7 +68,6 @@ struct device_operations {
 	const struct i2c_bus_operations *ops_i2c_bus;
 	const struct spi_bus_operations *ops_spi_bus;
 	const struct smbus_bus_operations *ops_smbus_bus;
-	const struct pci_bus_operations * (*ops_pci_bus)(struct device *dev);
 	const struct pnp_mode_ops *ops_pnp_mode;
 };