The Header Register set is always present for FPGA Management Engine (FME),
this patch implements init and uinit function for header sub feature and
introduces several read-only sysfs interfaces for the capability and
status.

Sysfs interfaces:
* /sys/class/fpga_region/<regionX>/<dfl-fme.x>/ports_num
  Read-only. Number of ports implemented

* /sys/class/fpga_region/<regionX>/<dfl-fme.x>/bitstream_id
  Read-only. Bitstream (static FPGA region) identifier number. It contains
  the detailed version and other information of this static FPGA region.

* /sys/class/fpga_region/<regionX>/<dfl-fme.x>/bitstream_metadata
  Read-only. Bitstream (static FPGA region) meta data. It contains the
  synthesis date, seed and other information of this static FPGA region.
Signed-off-by: Tim Whisonant <tim.whisonant@intel.com>
Signed-off-by: Enno Luebbers <enno.luebbers@intel.com>
Signed-off-by: Shiva Rao <shiva.rao@intel.com>
Signed-off-by: Christopher Rauer <christopher.rauer@intel.com>
Signed-off-by: Kang Luwei <luwei.kang@intel.com>
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Wu Hao <hao.wu@intel.com>
Acked-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>