hwmon: (sch56xx-common) Simplify sch56xx_device_add

Use platform_device_register_simple() instead of
manually calling platform_device_alloc()/platform_device_add().

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20210508131457.12780-5-W_Armin@gmx.de


Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>