TT#56007 TT#55864 leave xt_RTPENGINE loaded after stop

There might be a firewall script that installs and manages the
xt_RTPENGINE rules even if rtpengine isn't running at the point. Leave
the module loaded if possible and unload it only for a package removal
or upgrade.

Change-Id: I5a35e965379aebd757a45883f82bbcb5fa2412e8
(cherry picked from commit 9c6677d2fd)

debian/ngcp-rtpengine-iptables-setup

@@ -81,7 +81,6 @@ firewall_teardown()
 
   iptables -D rtpengine -p udp -j RTPENGINE --id "$TABLE" 2>/dev/null
   ip6tables -D rtpengine -p udp -j RTPENGINE --id "$TABLE" 2>/dev/null
-  rmmod $MODNAME 2>/dev/null
 }
 
 case "$1" in

debian/ngcp-rtpengine-kernel-dkms.prerm

@@ -4,6 +4,7 @@ set -e
 
 package=ngcp-rtpengine-kernel-dkms
 name=ngcp-rtpengine
+modname=xt_RTPENGINE
 
 version=$(dpkg-query -W -f="\${Version}" "$package" \
         |rev|cut -d- -f2-|rev|cut -d':' -f2|tr -d "\n")
@@ -17,6 +18,7 @@ fi
 # make sure it's not running
 if [ -x /etc/init.d/ngcp-rtpengine-daemon ] ; then
 	invoke-rc.d ngcp-rtpengine-daemon stop || true
+	rmmod "$modname" 2>/dev/null || true
 fi
 
 if [ "$VIRT" = "yes" ]; then