debian: don't explicitely call update-rc.d.

debhelper will do that for us.

Fixes duplicate-updaterc.d-calls-in-postinst lintian warning.

debian/nginx.postinst

diff --git a/debian/nginx.postinst b/debian/nginx.postinst
index 8edc9e6..4932ec3 100644
--- a/debian/nginx.postinst
+++ b/debian/nginx.postinst
@@ -28,7 +28,6 @@
         /etc/init.d/nginx upgrade || echo \
             "Binary upgrade failed, please check nginx's error.log"
     else
-        update-rc.d nginx defaults >/dev/null
         if [ -x "`which invoke-rc.d 2>/dev/null`" ]; then
             invoke-rc.d nginx start || true
         else