Add pnp_devfn_t and use with __SIMPLE_DEVICE__

Declare the functions that may be used in both romstage and ramstage
with simple device model. This will later allow to define PNP access
functions for ramstage using the inlined functions from romstage.

Change-Id: I2a0bd8194acaf9c4c7252a29376eec363397e3a6
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/3871
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>

src/include/device/device.h

@@ -12,6 +12,7 @@ struct device;
 #ifndef __SIMPLE_DEVICE__
 typedef struct device * device_t;
 typedef u32 pci_devfn_t;
+typedef u32 pnp_devfn_t;
 struct pci_operations;
 struct pci_bus_operations;
 struct smbus_bus_operations;