gpio: zynq: Provided workaround for GPIO

This patch provides workaround in the gpio driver
for Zynq and ZynqMP Platforms by reading pin value
of EMIO banks through DATA register as it was unable
to read the value of it from DATA_RO register.

Signed-off-by: Swapna Manupati <swapnam@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>