msm: thermal: Fix vdd restriction frequency apply code in KTM

KTM right now applies the vdd restriction to APPS,
only if the rail needs frequency mitigation and if clock
plan is initialized.
Otherwise it assumes the rail to be a voltage rail and
applies the voltage floor.

This logic will fail for APPS rail when the clock
plan is not initialized for a particular cluster.

Fix this logic to skip the vdd restriction apply
for APPS rail if clock plan is not initialized.

Change-Id: I46945b6a73794198bdc9a3a4a8a7bb25967e590f
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>