mfd: hi6421-pmic: Fix module autoload for OF platform driver

This platform driver has a OF device ID table but the OF module
alias information is not created so module autoloading won't work.

Signed-off-by: Luis de Bethencourt <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/mfd/hi6421-pmic-core.c

···
 	{ .compatible = "hisilicon,hi6421-pmic", },
 	{ },
 };
+MODULE_DEVICE_TABLE(of, of_hi6421_pmic_match_tbl);
 
 static struct platform_driver hi6421_pmic_driver = {
 	.driver = {