gluon-setup-mode: execute bootcount initscript in setup-mode

Currently Gluon does not execute the bootcount scripts when booting in
setup-mode.

While this is usually not issue after the first installation has
completed, it might lead to devices with an A/B partition layout to
switch active partitions after the device has been rebooted multiple
times before the initial configuration.

Fix this by executing the bootcount reset initscript.

Signed-off-by: David Bauer <mail@david-bauer.net>
(cherry picked from commit 5c064002)

package/gluon-setup-mode/files/lib/gluon/setup-mode/rc.d/S11bootcount

+#!/bin/sh /etc/rc.common
+
+if [ -x /etc/init.d/bootcount ] && /etc/init.d/bootcount enabled; then
+	. /etc/init.d/bootcount
+fi