Enable FPGA programming support for Zynq-7000

[fsagbuya]

Description

NOTE: This PR is based on the changes in PR #28. Please merge PR #28 before reviewing this.

This patch enables the user-space interface for sysfs that is necessary to program FPGA's PL part. Enable programming using fpga-manager and device-tree overlay.

See: https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18841645/Solution+Zynq+PL+Programming+With+FPGA+Manager

Changes:

• add device tree overlay configfs patch
• add xilinx fpga manager patch
• apply xilinx fpga support patches