gpio: zynq: Mask non-wakeup GPIO interrupts on suspend

Added flag to the GPIO chip so that IRQ from non-wakeup GPIO will
not wake the system.

Signed-off-by: Ezra Savard <ezra.savard@xilinx.com>
Reviewed-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>