net: netconsole: Eliminate redundant setting of enabled field

When disabling a netconsole target, enabled_store() is called with
enabled=false. Currently, this results in updating the nt->enabled
field twice:

1. Inside the if/else block, with the target_list_lock spinlock held
2. Later, without the target_list_lock

This patch eliminates the redundancy by setting the field only once,
improving efficiency and reducing potential race conditions.

Signed-off-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20240709144403.544099-3-leitao@debian.org


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