sysctl: remove redundant code
The xstrdup function calls strdup internally, and strdup will apply for memory internally and needs to be released externally. The function calls xstrdup(name) twice, but only releases the memory requested by the second call. The first call of xstrdup(name) is meaningless, so it is recommended to delete it.
signed-off-by: zhoujie zhoujie133@huawei.com