package/wpa_supplicant: Fix systemd service for new DBus bus name

package/wpa_supplicant: Fix systemd service for new DBus bus name

systemd service files were supplied with old DBus bus name. After
service activation systemd was waiting for appearance of specified bus
name to consider it started successfully. However, if wpa_supplicant was
compiled only with new dbus interface name, then systemd didn't notice
configured (old) DBus bus name appearance. In the end service was
considered malfunctioning and it was deactivated.

Add upstreamable patch [1], which updates systemd service BusName
property according to configured DBus interface version.

[1] http://lists.infradead.org/pipermail/hostap/2016-April/035599.html

Signed-off-by: Marcin Niestroj <m.niestroj@grinn-global.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>