net: openvswitch: Release reference to netdev

dev_get_by_name will provide a reference on the netdev. So ensure that
the reference of netdev is released after completed.

Fixes: 2540088b ("net: openvswitch: Check vport netdev name")
Signed-off-by: Jun Gu <jun.gu@easystack.cn>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Link: https://lore.kernel.org/r/20240423073751.52706-1-jun.gu@easystack.cn


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