fsck.ubifs: Recover isize

fsck.ubifs: Recover isize

This is the 5/18 step of fsck. Recover isize. There could be following
steps and possible errors:
 Step 1. Traverse size tree, lookup corresponding inode from TNC
  a. corrupted node searched from TNC: skip node for danger mode and
     normal mode with 'yes' answer, other modes will exit.
  b. corrupted index node read from TNC: danger mode with rebuild_fs and
     normal mode with 'yes' answer will turn to rebuild filesystem, other
     modes will exit.
 Step 2. update isize for inode. Keep <inum, isize> in size tree for check
 mode, update inode node in place for other modes.

Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>