hwmon: (sch56xx) Remove unneeded linux/miscdevice.h include

drivers/hwmon/sch56xx-common.c does not contain any miscdevice so the
inclusion of linux/miscdevice.h is uncessary.

Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>