drivers: thermal: lmh-dcvsh: Allow boost frequency

CPUs having the support for boost frequency can allow the CPUs to operate
at this high frequency when the device is under thermal envelope. In
those cases LMH-DCVSh software should allow the boost frequency.

In order to support this, vote for a very high frequency value when HLOS
has no scaling max request. This will not prevent the boost frequency
functionality.

Change-Id: Ia13fbb867134cf53459d0c7fbd1a5abb31dd1799
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>