mfd: Add MODULE_DEVICE_TABLE to pcf50633-core

The device table is required to load modules based on modaliases.
After adding the MODULE_DEVICE_TABLE, below entries will be added to
modules.alias:
alias i2c:pcf50633 pcf50633

Signed-off-by: Axel Lin <[e-mail]>
Acked-by: Harald Welte <[e-mail]>
Signed-off-by: Samuel Ortiz <[e-mail]>

drivers/mfd/pcf50633-core.c

···
 	{"pcf50633", 0x73},
 	{/* end of list */}
 };
+MODULE_DEVICE_TABLE(i2c, pcf50633_id_table);
 
 static struct i2c_driver pcf50633_driver = {
 	.driver = {