msm: thermal: Initialize Vdd scaling max frequency variable

Currently Vdd scaling max frequency variable is not initialized,
which leads to wrong aggregation of thermal cpu scaling max frequency
request especially during KTM boot up mitigation. Initialize low
temperature scaling max frequency variable to UINT_MAX at
probe function.

Change-Id: I0220b9390cac33d40af0e4419d7451553ba6c5b5
Signed-off-by: Manaf Meethalavalappu Pallikunhi <manafm@codeaurora.org>