This patch reverts the workaround for errata #814670: "A57 DMB barrier does not
guarantee observation of the effects of a cache maintenance operation". Cache
maintenance by set/way operations is performed only for processor power
down. BROADCASTCACHEMAINT = 1'b1 on the Cortex-A57 macro on Juno. Hence this
erratum will have no impact.

Change-Id: I6824044c963b28d59aed39712a6da376dc053b82