gpio: davinci: add support of module build

Added module build support for the davinci gpio driver
Signed-off-by: Guillaume La Roque <glaroque@baylibre.com>
Signed-off-by: Nicolas Frayer <nfrayer@baylibre.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/Kconfig

@@ -228,7 +228,7 @@ config GPIO_CLPS711X
 	  Say yes here to support GPIO on CLPS711X SoCs.
 
 config GPIO_DAVINCI
-	bool "TI Davinci/Keystone GPIO support"
+	tristate "TI Davinci/Keystone GPIO support"
 	default y if ARCH_DAVINCI
 	depends on (ARM || ARM64) && (ARCH_DAVINCI || ARCH_KEYSTONE || ARCH_K3)
 	help

drivers/gpio/gpio-davinci.c

@@ -727,3 +727,14 @@ static int __init davinci_gpio_drv_reg(void)
 	return platform_driver_register(&davinci_gpio_driver);
 }
 postcore_initcall(davinci_gpio_drv_reg);
+
+static void __exit davinci_gpio_exit(void)
+{
+	platform_driver_unregister(&davinci_gpio_driver);
+}
+module_exit(davinci_gpio_exit);
+
+MODULE_AUTHOR("Jan Kotas <jank@cadence.com>");
+MODULE_DESCRIPTION("DAVINCI GPIO driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gpio-davinci");