lpm-levels: Fix warning for non-psci targets

During LPM probe warning is coming for non-psci
targets that have no SPM device associated for
cluster which is expected.

Correct condition and warn only if target is using
psci and if no SPM device is associated for cluster.

Change-Id: I4968a33ff2f753bd4eb163e96d2dbb88b134e787
Signed-off-by: Maulik Shah <mkshah@codeaurora.org>