PCI: xilinx: Modifying AXI PCIe Host Bridge driver to work on both Zynq and Microblaze

PCI: xilinx: Modifying AXI PCIe Host Bridge driver to work on both Zynq and Microblaze

Modifying Xilinx AXI PCIe Host Bridge Soft IP driver to work on both
Zynq and Microblaze Architectures.
With these modifications drivers/pci/host/pcie-xilinx.c, will
work on both Zynq and Microblaze Architectures.

Signed-off-by: Bharat Kumar Gogada <bharatku@xilinx.com>
Signed-off-by: Ravi Kiran Gummaluri <rgummal@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>