openvpn: fix arguments passing to wrapped up and down scripts

openvpn: fix arguments passing to wrapped up and down scripts

With the introduction of the generic OpenVPN hotplug mechanism, wrapped
--up and --down scripts got the wrong amount and order of arguments passed,
breaking existing configurations and functionality.

Fix this issue by passing the same amount of arguments in the same expected
order as if the scripts were executed by the OpenVPN daemon directly.

Ref: https://github.com/openwrt/openwrt/pull/1596#issuecomment-668935156
Fixes: 8fe9940db6 ("openvpn: add generic hotplug mechanism")
Signed-off-by: Jo-Philipp Wich <jo@mein.io>