netdev-genl: Hold rcu_read_lock in napi_get

Hold rcu_read_lock in netdev_nl_napi_get_doit, which calls napi_by_id
and is required to be called under rcu_read_lock.

Cc: stable@vger.kernel.org
Fixes: 27f91aaf ("netdev-genl: Add netlink framework functions for napi")
Signed-off-by: Joe Damato <jdamato@fastly.com>
Link: https://patch.msgid.link/20241114175157.16604-1-jdamato@fastly.com


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