rds: Incorrect reference counting in TCP socket creation

rds: Incorrect reference counting in TCP socket creation

Commit a670499f5a9a ("rds: tcp: use sock_create_lite() to create the
accept socket") has a reference counting issue in TCP socket creation
when accepting a new connection.  The code uses sock_create_lite() to
create a kernel socket.  But it does not do __module_get() on the
socket owner.  When the connection is shutdown and sock_release() is
called to free the socket, the owner's reference count is decremented
and becomes incorrect.  Note that this bug only shows up when IPv6 is
configured as a kernel module.

Orabug: 27602824

Signed-off-by: Ka-Cheong Poon <ka-cheong.poon@oracle.com>
Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>