UBUNTU: [Debian] linux-image-extra postrm is not needed on purge

Signed-off-by: Andy Whitcroft <apw@canonical.com>
(cherry picked from commit 920e8acdb5b860086618e436f572717b631e65ec)
Signed-off-by: Andy Whitcroft <apw@canonical.com>

debian/control-scripts/extra-post

@@ -2,7 +2,7 @@
 set -e
 
 case "$0::$1" in
-*.postinst::configure|*.postrm::remove|*.postrm::purge)
+*.postinst::configure|*.postrm::remove)
 	depmod -a -F /boot/System.map-=V =V || true
 	for dir in "/etc/kernel/postinst.d" "/etc/kernel/postinst.d/=V"
 	do