ARM: mvebu: mark armada_370_xp_pmsu_idle_prepare() as static

The armada_370_xp_pmsu_idle_prepare() function is only used internally
to pmsu.c, so there's no reason to not use the static qualifier.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1401116474-31221-1-git-send-email-thomas.petazzoni@free-electrons.com


Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>