ubifs: journal: Handle xattrs like files

If an inode hosts xattrs, create deletion entries for each
inode. That way we can make sure that upon journal replay UBIFS
can find find all xattr inodes.
Otherwise it can happen that GC consumed already a LEB which contained
parts of the TNC that pointed to the xattrs and we no longer
find all xattr inodes, which will confuse the LPT and cause
space allocation issues.

Reported-by: Stefan Agner <stefan@agner.ch>
Fixes: 1e51764a ("UBIFS: add new flash file system")
Signed-off-by: Richard Weinberger <richard@nod.at>