gpio: tps68470: Allow building as module

The gpio-tps68470 driver binds to a tps68470-gpio platform-device which
itself gets instantiated by a special MFD driver from
drivers/platform/x86/intel/int3472/tps68470.c

This MFD driver itself can be built as a module, so it makes no sense to
force the gpio-tps68470 driver to always be built-in.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/gpio/Kconfig

@@ -1380,7 +1380,7 @@ config GPIO_TPS65912
 	  This driver supports TPS65912 GPIO chip.
 
 config GPIO_TPS68470
-	bool "TPS68470 GPIO"
+	tristate "TPS68470 GPIO"
 	depends on INTEL_SKL_INT3472
 	help
 	  Select this option to enable GPIO driver for the TPS68470
@@ -1390,10 +1390,6 @@ config GPIO_TPS68470
 	  input or output as appropriate, the sensor related GPIOs
 	  are "output only" GPIOs.
 
-	  This driver config is bool, as the GPIO functionality
-	  of the TPS68470 must be available before dependent
-	  drivers are loaded.
-
 config GPIO_TQMX86
 	tristate "TQ-Systems QTMX86 GPIO"
 	depends on MFD_TQMX86 || COMPILE_TEST

drivers/gpio/gpio-tps68470.c

@@ -154,5 +154,8 @@ static struct platform_driver tps68470_gpio_driver = {
 	},
 	.probe = tps68470_gpio_probe,
 };
+module_platform_driver(tps68470_gpio_driver);
 
-builtin_platform_driver(tps68470_gpio_driver)
+MODULE_ALIAS("platform:tps68470-gpio");
+MODULE_DESCRIPTION("GPIO driver for TPS68470 PMIC");
+MODULE_LICENSE("GPL v2");