netlabel: Correct function name netlbl_mgmt_add() in the kerneldoc comments

Fix the following W=1 kernel build warning(s):

 net/netlabel/netlabel_mgmt.c:78: warning: expecting prototype for netlbl_mgmt_add(). Prototype was for netlbl_mgmt_add_common() instead
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NXiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/netlabel/netlabel_mgmt.c

@@ -63,7 +63,7 @@ static const struct nla_policy netlbl_mgmt_genl_policy[NLBL_MGMT_A_MAX + 1] = {
  */
 
 /**
- * netlbl_mgmt_add - Handle an ADD message
+ * netlbl_mgmt_add_common - Handle an ADD message
  * @info: the Generic NETLINK info block
  * @audit_info: NetLabel audit information
  *