Revert "fs/sync.c : fix build error"

This reverts commit 02f072ebd215786f6ceb863e90393cdb35c1917c.
Revert "afsync: replace fput() with fput_light() accordingly"

This reverts commit afedafb345ffb2215970b56060dc3e9b447630f2.
Revert "add f2fs as filesystem to async fsync"

This reverts commit e41a4a53d1b3c9afa89e1a020db77ba07268acb2.
Revert "async fsync from htc one (ported by faux123)"

This reverts commit 0dc073b2ac04998fe57a923b3940aa3ff37b129c.
Revert "block: separate priority boosting from REQ_META"

This reverts commit 44100463b0bd1176f3f9d8cf1bf67f95ad003482.
Revert "block: remove READ_META and WRITE_META"

This reverts commit 2a935c7dd5dcff5ebc4b9afed6ed38030577ecb1.
fs/f2fs: Add Missing REQ_PRIO defines