thermal: mediatek: add common index of vts settings.

Each project has different number of vts settings.
For the MT2701 just have to set three vts, but the
original code flow add five unnecessary vts.
Add common index of vts settings for scalablity,
and reduce the setting of unnecessary vts.

Signed-off-by: Michael Kao <michael.kao@mediatek.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>