device/device_util: Add string for DEVICE_PATH_NONE

Add string for DEVICE_PATH_NONE in dev_path. The enum DEVICE_PATH_NONE
can be translated to string and shouldn't be translated by
"Unknown device path type: 0".

Makes console output a lot prettier and readable.

Note: DEVICE_PATH_NONE is used on dummy devices for hotpluggable slots.

Change-Id: I08d471d8217f966e80daefe2d9971e357defde62
Signed-off-by: Patrick Rudolph <siro@das-labor.org>
Reviewed-on: https://review.coreboot.org/22272
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

src/device/device_util.c

@@ -274,6 +274,9 @@ const char *dev_path(device_t dev)
 		memcpy(buffer, "<null>", 7);
 	} else {
 		switch(dev->path.type) {
+		case DEVICE_PATH_NONE:
+			memcpy(buffer, "NONE", 5);
+			break;
 		case DEVICE_PATH_ROOT:
 			memcpy(buffer, "Root Device", 12);
 			break;