Fix deviceid test when model present but no vendor

Fixes small bug introduced in b26c5a4

Without this, the error message was appended to, and e.g. `device` could
end up as "UNKNOWN vendor/modelAFilterX" instead of the expected
"AFilterX"

Author: doismellburning

src/deviceid.c

@@ -551,6 +551,11 @@ void deviceid_decode_dest (char *dest, char *device, size_t device_size)
 	      strlcat (device, " ", device_size);
 	    }
 
+	    if (ptocalls[n].vendor == NULL && ptocalls[n].model != NULL) {
+	      // If we don't have a vendor, but do have a model, wipe the error message
+	      strlcpy (device, "", device_size);
+	    }
+
 	    if (ptocalls[n].model != NULL) {
 	      strlcat (device, ptocalls[n].model, device_size);
 	    }