macsec: Fix invalid error code set

'ret' is defined twice in macsec_changelink(), when it is set in macsec_is_offloaded
case, it will be invalid before return.

Fixes: 3cf3227a ("net: macsec: hardware offloading infrastructure")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Saeed Mahameed <saeed@kernel.org>
Reviewed-by: Antoine Tenart <atenart@kernel.org>
Link: https://lore.kernel.org/r/20221118011249.48112-1-yuehaibing@huawei.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>