We implement the SO_SNDLOWAT etc not to be settable and return
ENOPROTOOPT per 1003.1g 7. Move the comment to appropriate
position and update the reference.
Signed-off-by: YOSHIFUJI Hideaki <hideaki.yoshifuji@miraclelinux.com> Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> Signed-off-by: David S. Miller <davem@davemloft.net>