macsec: fix detection of RXSCs when toggling offloading

stable inclusion
from stable-v5.10.155
commit 9dc7503bae33046c6301562f7e03d5352e6f8c50
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=9dc7503bae33046c6301562f7e03d5352e6f8c50



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[ Upstream commit 80df4706 ]

macsec_is_configured incorrectly uses secy->n_rx_sc to check if some
RXSCs exist. secy->n_rx_sc only counts the number of active RXSCs, but
there can also be inactive SCs as well, which may be stored in the
driver (in case we're disabling offloading), or would have to be
pushed to the device (in case we're trying to enable offloading).

As long as RXSCs active on creation and never turned off, the issue is
not visible.

Fixes: dcb780fb ("net: macsec: add nla support for changing the offloading selection")
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>