Merge tag 'upstream-4.5-rc1' of git://git.infradead.org/linux-ubifs

Pull UBI/UBIFS updates from Richard Weinberger:
 "This contains three changes - two cleanups and one UBI wear leveling
  improvement by Sebastian Siewior"

* tag 'upstream-4.5-rc1' of git://git.infradead.org/linux-ubifs:
  ubifs: Use XATTR_*_PREFIX_LEN
  UBIFS: add a comment in key.h for unused parameter
  mtd: ubi: wl: avoid erasing a PEB which is empty