gpio: add TB10x GPIO driver

The GPIO driver for the Abilis Systems TB10x series of SOCs based on ARC700
CPUs. It supports GPIO control and GPIO interrupt generation. This driver
works in conjunction with the TB10x pinctrl driver.

Signed-off-by: Sascha Leuenberger <sascha.leuenberger@abilis.com>
Signed-off-by: Christian Ruppert <christian.ruppert@abilis.com>
Acked-by: Kumar Gala <galak@codeaurora.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index b6ed304..661ca82 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -360,6 +360,10 @@
 	  Select this to support Aeroflex Gaisler GRGPIO cores from the GRLIB
 	  VHDL IP core library.
 
+config GPIO_TB10X
+	bool
+	select OF_GPIO
+
 comment "I2C GPIO expanders:"
 
 config GPIO_ARIZONA