deployment: do not create /etc/ngcp_ha_role + /etc/ngcp_ha_master if values are unset

Otherwise we're creating broken systems which don't work as supposed.
And while at it do not append variables to files but instead override
any existing values, otherwise we might have broken config files.

From: Michael Prokop <mprokop@sipwise.com>

deployment.sh

@@ -734,8 +734,19 @@ ff02::2         ip6-allrouters
 EOF
 
 if "$PRO_EDITION" ; then
-  echo $CROLE >> $TARGET/etc/ngcp_ha_role
-  echo $CMASTER >> $TARGET/etc/ngcp_ha_master
+  if [ -n "$CROLE" ] ; then
+    echo "Writing $CROLE to /etc/ngcp_ha_role"
+    echo $CROLE > $TARGET/etc/ngcp_ha_role
+  else
+    echo "No role definition set, not creating /etc/ngcp_ha_role"
+  fi
+
+  if [ -n "$CMASTER" ] ; then
+    echo "Writing $CMASTER to /etc/ngcp_ha_master"
+    echo $CMASTER > $TARGET/etc/ngcp_ha_master
+  else
+    echo "No mgmgt master set, not creating /etc/ngcp_ha_master"
+  fi
 fi
 
 if "$PRO_EDITION" && [[ $(imvirt) != "Physical" ]] ; then