fpga manager: Adding FPGA Manager support for Xilinx Zynq 7000

This commit adds FPGA Manager support for the Xilinx Zynq chip.
The code borrows some from the xdevcfg driver in Xilinx'
vendor tree.

Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>