Asynchronous Fsync: initial extraction of Async Fsync from HTC

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

Conflicts:
	fs/Kconfig
	fs/sync.c
	include/linux/fs.h

Change-Id: Iec5e1651e7ae9ed85e49f8772f3b3a9c9082d465