What:		/sys/bus/platform/devices/dfl-port.0/id
Date:		June 2018
KernelVersion:	4.19
Contact:	Wu Hao <hao.wu@intel.com>
Description:	Read-only. It returns id of this port. One DFL FPGA device
		may have more than one port. Userspace could use this id to
		distinguish different ports under same FPGA device.