zynqmp: gpio: Add support for zynqmp gpio modepin driver

ZynqMP modepin driver has capability to get/set/check status of modepin
gpios. These modepins are accessed using xilinx firmware. In modepin
register, [3:0] bits set direction, [7:4] bits read IO, [11:8] bits
set/clear IO.

Signed-off-by: T Karthik Reddy <t.karthik.reddy@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Link: https://lore.kernel.org/r/2d802d98fd56d95d764532a33e844d935e0cebb3.1635505900.git.michal.simek@xilinx.com
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 3c851b3..3eb77f5 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -69,3 +69,4 @@
 obj-$(CONFIG_SIFIVE_GPIO)	+= sifive-gpio.o
 obj-$(CONFIG_NOMADIK_GPIO)	+= nmk_gpio.o
 obj-$(CONFIG_MAX7320_GPIO)	+= max7320_gpio.o
+obj-$(CONFIG_ZYNQMP_GPIO_MODEPIN)	+= zynqmp_gpio_modepin.o