devicetree: Search PnP device node from the tree by path

Copied from device_util.c with added ROMSTAGE_CONST.

Change-Id: If872631ed96a79b9a0b15e09382d6f81098c8db3
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/8297
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>

src/include/device/device.h

@@ -261,6 +261,7 @@ ROMSTAGE_CONST struct device *dev_find_next_pci_device(
 						ROMSTAGE_CONST struct device *previous_dev);
 ROMSTAGE_CONST struct device * dev_find_slot_on_smbus (unsigned int bus,
 							unsigned int addr);
+ROMSTAGE_CONST struct device * dev_find_slot_pnp(u16 port, u16 device);
 
 #endif