gpio: Added support to Zynq Ultrascale+ MPSoC

Added support to Zynq Ultrascale+ MPSoC on the existing zynq
gpio driver.

Signed-off-by: Anurag Kumar Vulisha <anuragku@xilinx.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>