ARM: tegra: convert CONFIG_TEGRA_GPIO to Kconfig

Future chips will contain different GPIO HW. This change will enable
future SoC support to select the appropriate GPIO driver for their HW,
in a future-looking fashion, using Kconfig.

TEGRA_GPIO is not simply selected by TEGRA_COMMON (even though all
current Tegra chips used this GPIO HW) to simplify the later addition
of support for Tegra SoCs that use different GPIO HW.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 93a7e8c..f730744 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -109,6 +109,13 @@
 	  of 'anonymous' GPIOs that do not belong to any device or bank.
 	  Select a suitable value depending on your needs.
 
+config TEGRA_GPIO
+	bool "Tegra20..210 GPIO driver"
+	depends on DM_GPIO
+	help
+	  Support for the GPIO controller contained in NVIDIA Tegra20 through
+	  Tegra210.
+
 config GPIO_UNIPHIER
 	bool "UniPhier GPIO"
 	depends on ARCH_UNIPHIER