drivers/hwmon/w83791d.c: fix unused var warning

drivers/hwmon/w83791d.c: In function `w83791d_probe':
drivers/hwmon/w83791d.c:1049: warning: unused variable `val1'

Signed-off-by: Michael Borisov <niro@tut.by>
Cc: "Mark M. Hoffman" <mhoffman@lightlink.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>