ARM: mvebu: do not check machine in mvebu_pm_init()

The mvebu_pm_init() initializes the support for suspend/resume, and
before doing that, it checks if we are on a board on which
suspend/resume is actually supported. However, this check is already
done by mvebu_armada_xp_gp_pm_init(), and there is no need to
duplicate the check: callers of mvebu_pm_init() should now what they
are doing.

This commit is done in preparation to the addition of suspend/resume
support on Armada 38x.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>