gpio/tegra: Use engineering names in DT compatible property

Engineering names are more stable than marketing names. Hence, use them
for Device Tree compatible properties instead.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

Documentation/devicetree/bindings/gpio/gpio_nvidia.txt

 NVIDIA Tegra 2 GPIO controller
 
 Required properties:
-- compatible : "nvidia,tegra250-gpio"
+- compatible : "nvidia,tegra20-gpio"
 - #gpio-cells : Should be two. The first cell is the pin number and the
   second cell is used to specify optional parameters (currently unused).
 - gpio-controller : Marks the device node as a GPIO controller.

drivers/gpio/gpio-tegra.c

@@ -347,7 +347,7 @@ static int __init tegra_gpio_init(void)
 	 * driver is converted into a platform_device
 	 */
 	tegra_gpio_chip.of_node = of_find_compatible_node(NULL, NULL,
-						"nvidia,tegra250-gpio");
+						"nvidia,tegra20-gpio");
 #endif /* CONFIG_OF_GPIO */
 
 	gpiochip_add(&tegra_gpio_chip);