Asynchronous Fsync: initial extraction of Async Fsync from HTC

Signed-off-by: Paul Reioux <reioux@gmail.com>

Conflicts:
	fs/sync.c
fs/Kconfig: fix warning related to AYSNC_FSYNC patch

Signed-off-by: Paul Reioux <reioux@gmail.com>
disable qcache and enable zcache