macsec: clean up local variables in macsec_notify

For all events, we need to loop over the list of secys, so let's move
the common variables out of the switch/case.

Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/9b8996af518fbeb3b7d527feb15d5788495e3108.1730929545.git.sd@queasysnail.net


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