ARM: mvebu: split again armada_370_xp_pmsu_idle_enter() in PMSU code

ARM: mvebu: split again armada_370_xp_pmsu_idle_enter() in PMSU code

do_armada_370_xp_cpu_suspend() and armada_370_xp_pmsu_idle_prepare(),
have been merged into a single function called
armada_370_xp_pmsu_idle_enter() by the commit "bbb92284b6c8 ARM:
mvebu: slightly refactor/rename PMSU idle related functions", in
prepare for the introduction of the CPU hotplug support for Armada XP.

But for cpuidle the prepare function will be common to all the mvebu
SoCs that use the PMSU, while the suspend function will be specific to
each SoC. Keeping the prepare function separate will help reducing
code duplication while new SoC support is added.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1406120453-29291-2-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>