staging: fpgaboot: Xilinx FPGA firmware download driver

This driver downloads Xilinx FPGA firmware using gpio pins.
It loads Xilinx FPGA bitstream format firmware image and
program the Xilinx FPGA using SelectMAP (parallel) mode.

Signed-off-by: Insop Song <insop.song@gainspeed.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>