tcp: Add missing braces to do_tcp_setsockopt

[ Upstream commit e2e5c4c07caf810d7849658dca42f598b3938e21 ]

Signed-off-by: Dave Jones <davej@fedoraproject.org>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>