f2fs: initialize locks earlier in f2fs_fill_super()

syzbot is reporting lockdep warning at f2fs_handle_error() [1], for
spin_lock(&sbi->error_lock) is called before spin_lock_init() is called.
For safe locking in error handling, move initialization of locks (and
obvious structures) in f2fs_fill_super() to immediately after memory
allocation.

Link: https://syzkaller.appspot.com/bug?extid=40642be9b7e0bb28e0df

 [1]
Reported-by: syzbot <syzbot+40642be9b7e0bb28e0df@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+40642be9b7e0bb28e0df@syzkaller.appspotmail.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>