ubus: update to the latest version, fixes a rare deadlock with multiple synchronous invoke/notify calls

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@36603 3c298f89-4303-0410-b956-a3cf2f4a3e73