Add pci_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 PCI access
functions for ramstage using the inlined functions from romstage.

Change-Id: I32ff622883ceee4628e6b1b01023b970e379113f
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/3508
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>

src/southbridge/amd/cimx/sb700/reset.c

@@ -36,7 +36,7 @@ static inline void set_bios_reset(void)
 {
 	u32 nodes;
 	u32 htic;
-	device_t dev;
+	pci_devfn_t dev;
 	int i;
 
 	nodes = ((pci_read_config32(PCI_DEV(CONFIG_CBB, CONFIG_CDB, 0), 0x60) >> 4) & 7) + 1;