macsec: fix memory leaks when skb_to_sgvec fails

[ Upstream commit 5aba2ba5030b66a6f8c93049b718556f9aacd7c6 ]

Fixes: cda7ea690350 ("macsec: check return value of skb_to_sgvec always")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>