gpio: ts4800: Fix module autoload

If the driver is built as a module, autoload won't work because the module
alias information is not filled. So user-space can't match the registered
device with the corresponding module.

Export the module alias information using the MODULE_DEVICE_TABLE() macro.

Before this patch:

$ modinfo drivers/gpio/gpio-ts4800.ko | grep alias
$

After this patch:

$ modinfo drivers/gpio/gpio-ts4800.ko | grep alias
alias:          of:N*T*Ctechnologic,ts4800-gpioC*
alias:          of:N*T*Ctechnologic,ts4800-gpio
Signed-off-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-ts4800.c

@@ -66,6 +66,7 @@ static const struct of_device_id ts4800_gpio_of_match[] = {
 	{ .compatible = "technologic,ts4800-gpio", },
 	{},
 };
+MODULE_DEVICE_TABLE(of, ts4800_gpio_of_match);
 
 static struct platform_driver ts4800_gpio_driver = {
 	.driver = {