Merge changes I5ae9d08b,I5cbbd7eb,Idb389223 into integration

* changes:
  plat: marvell: armada: Building ${DOIMAGETOOL} is only for a8k
  plat: marvell: armada: Fix including plat/marvell/marvell.mk file
  plat: marvell: armada: a3k: When WTP is empty do not define variables and targets which depends on it