net: sock.h: fix skb_steal_sock() kernel-doc

Fix warnings related to kernel-doc notation, and wording in
function description.

Signed-off-by: Lothar Rubusch <l.rubusch@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>