mmc: mediatek: 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/mmc/host/mtk-sd.ko | grep alias
$

After this patch:

$ modinfo drivers/mmc/host/mtk-sd.ko | grep alias
alias:          of:N*T*Cmediatek,mt8135-mmcC*
alias:          of:N*T*Cmediatek,mt8135-mmc
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/mtk-sd.c

@@ -1713,6 +1713,7 @@ static const struct of_device_id msdc_of_ids[] = {
 	{   .compatible = "mediatek,mt8135-mmc", },
 	{}
 };
+MODULE_DEVICE_TABLE(of, msdc_of_ids);
 
 static struct platform_driver mt_msdc_driver = {
 	.probe = msdc_drv_probe,