w1: w1_therm: fix build warning in w1_seq_show()

Fix the following build warning:

  drivers/w1/slaves/w1_therm.c: In function ‘w1_seq_show’:
  drivers/w1/slaves/w1_therm.c:2059:6: warning: variable ‘rv’ set but not used [-Wunused-but-set-variable]
    int rv;
        ^~

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20210518050415.615783-1-yangyingliang@huawei.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>