udf: remove redundant sys_tz declaration

sys_tz is already declared in include/linux/time.h

Cc: Jan Kara <jack@suse.cz>
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NJan Kara <jack@suse.cz>

fs/udf/udftime.c

@@ -81,8 +81,6 @@ static time_t year_seconds[MAX_YEAR_SECONDS] = {
 /*2038*/ SPY(68, 17, 0)
 };
 
-extern struct timezone sys_tz;
-
 #define SECS_PER_HOUR	(60 * 60)
 #define SECS_PER_DAY	(SECS_PER_HOUR * 24)