macsec: fix secy->n_rx_sc accounting

stable inclusion
from stable-v5.10.155
commit 7f4456f0119b8014ce61c38912d74fa4fd24092c
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7M5F4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7f4456f0119b8014ce61c38912d74fa4fd24092c



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[ Upstream commit 73a4b31c ]

secy->n_rx_sc is supposed to be the number of _active_ rxsc's within a
secy. This is then used by macsec_send_sci to help decide if we should
add the SCI to the header or not.

This logic is currently broken when we create a new RXSC and turn it
off at creation, as create_rx_sc always sets ->active to true (and
immediately uses that to increment n_rx_sc), and only later
macsec_add_rxsc sets rx_sc->active.

Fixes: c09440f7 ("macsec: introduce IEEE 802.1AE driver")
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: Antoine Tenart <atenart@kernel.org>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>