f2fs: update to latest version 3.4.y
f2fs: update to latest version 3.4.y [20140903]

* 6f69935  f2fs: support 3.4 by Jaegeuk Kim - 1 year, 3 months ago linux-3.4
* 5b1cbad  f2fs: need fsck.f2fs if the recovery was failed by Jaegeuk Kim - 7 days ago
* 60b1580  f2fs: handle bug cases by letting fsck.f2fs initiate by Jaegeuk Kim - 7 days ago
* 7cb5d0f  f2fs: add BUG cases to initiate fsck.f2fs by Jaegeuk Kim - 7 days ago
* ba88ebd  f2fs: need fsck.f2fs when f2fs_bug_on is triggered by Jaegeuk Kim - 7 days ago
* 3258dd6  f2fs: remain inconsistency information to initiate fsck.f2fs by Jaegeuk Kim - 7 days ago
* 4081363  f2fs: introduce F2FS_I_SB, F2FS_M_SB, and F2FS_P_SB by Jaegeuk Kim - 7 days ago
* b73e528  f2fs: reposition unlock_new_inode to prevent accessing invalid inode by Chao Yu - 11 days ago