hwmon: (w83793) Drop useless mutex

This is the same case as fschmd, from which the code was copied as far
as I can see. So the same clean-up applies:

The WDIOC_GETSUPPORT ioctl only needs a mutex because it operates on a
static variable. There is no good reason to keep this variable static,
so let's just make it non-static and drop the now useless mutex
altogether.

See the discussion at:
http://marc.info/?l=lm-sensors&m=125563869402323&w=2



Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>