kernel/sysctl-test: use SYSCTL_{ZERO/ONE_HUNDRED} instead of i_{zero/one_hundred}

It is better to use SYSCTL_ZERO and SYSCTL_ONE_HUNDRED instead of &i_zero
and &i_one_hundred, and then we can remove these two local variable.

No functional change.

Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>