cifs: remove unused variable

In smb3_punch_hole, variable cifsi set but not used, remove it.
In cifs_lock, variable netfid set but not used, remove it.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>