pwm: samsung: Use MODULE_DEVICE_TABLE() to include OF modalias

If the pwm-samsung driver is built as a module, modalias information is
not filled so the module is not autoloaded. Use the MODULE_DEVICE_TABLE()
macro to export the OF device ID so the module contains that information.
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-samsung.c

@@ -456,6 +456,7 @@ static const struct of_device_id samsung_pwm_matches[] = {
 	{ .compatible = "samsung,exynos4210-pwm", .data = &s5p64x0_variant },
 	{},
 };
+MODULE_DEVICE_TABLE(of, samsung_pwm_matches);
 
 static int pwm_samsung_parse_dt(struct samsung_pwm_chip *chip)
 {