hwmon: (fschmd) Drop useless mutex

As discussed one year ago, 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>