gpio: moxart: convert to use basic mmio gpio library

This patch converts MOXART GPIO driver to use basic_mmio_gpio
generic library.

Signed-off-by: Kamlakant Patel <kamlakant.patel@linaro.org>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Tested-by: Jonas Jensen <jonas.jensen@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 633ec21..e367296 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -200,6 +200,7 @@
 config GPIO_MOXART
 	bool "MOXART GPIO support"
 	depends on ARCH_MOXART
+	select GPIO_GENERIC
 	help
 	  Select this option to enable GPIO driver for
 	  MOXA ART SoC devices.