l3mdev: Correct function names in the kerneldoc comments

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

 net/l3mdev/l3mdev.c:111: warning: expecting prototype for l3mdev_master_ifindex(). Prototype was for l3mdev_master_ifindex_rcu() instead
 net/l3mdev/l3mdev.c:145: warning: expecting prototype for l3mdev_master_upper_ifindex_by_index(). Prototype was for l3mdev_master_upper_ifindex_by_index_rcu() instead

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l3mdev/l3mdev.c

@@ -103,7 +103,7 @@ unlock:
 EXPORT_SYMBOL_GPL(l3mdev_ifindex_lookup_by_table_id);
 
 /**
- *	l3mdev_master_ifindex - get index of L3 master device
+ *	l3mdev_master_ifindex_rcu - get index of L3 master device
  *	@dev: targeted interface
  */
 
@@ -136,7 +136,7 @@ int l3mdev_master_ifindex_rcu(const struct net_device *dev)
 EXPORT_SYMBOL_GPL(l3mdev_master_ifindex_rcu);
 
 /**
- *	l3mdev_master_upper_ifindex_by_index - get index of upper l3 master
+ *	l3mdev_master_upper_ifindex_by_index_rcu - get index of upper l3 master
  *					       device
  *	@net: network namespace for device index lookup
  *	@ifindex: targeted interface