ARM: mvebu: use a separate function to set the boot address of CPUs

Setting the start (or boot) address of a CPU is no more used only
during SMP bring up on Armada 370/XP, but it will also be used by the
CPU idle function of Armada XP, and by the Armada 38x SMP support.

Therefore this commit creates a separate PMSU function to set the boot
address of a CPU with the PMSU.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483433-25836-7-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483433-25836-7-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>