fstools: switch to ulog api

Update to git head in order to switch the block, mount_root etc. logging to
the common ulog() api for putting early boot messages into dmesg.

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@44545 3c298f89-4303-0410-b956-a3cf2f4a3e73