hwmon: (stts751) Remove an unused field in struct stts751_priv

In "struct stts751_priv", the 'smbus_timeout' field is unused.
Remove it.

Found with cppcheck, unusedStructMember.

Signed-off-by: Christophe JAILLET <[e-mail]>
Link: https://lore.kernel.org/r/94ccf9caaa[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>

drivers/hwmon/stts751.c

···
 	int event_max, event_min;
 	int therm;
 	int hyst;
-	bool smbus_timeout;
 	int temp;
 	unsigned long last_update, last_alert_update;
 	u8 config;