net/netlink: make sure the headers line up actual value output

Making sure the headers line up properly with the actual value output of the command
`cat /proc/net/netlink`

Before the patch:
<sk       Eth Pid    Groups   Rmem     Wmem     Dump     Locks     Drops     Inode
<ffff8cd2c2f7b000 0   909    00000550 0        0        0 2        0        18946

After the patch:
>sk               Eth Pid        Groups   Rmem     Wmem     Dump  Locks    Drops    Inode
>0000000033203952 0   897        00000113 0        0        0     2        0        14906

Signed-off-by: Bo YU <tsu.yubo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>