msm: thermal: Set vdd restriction initialize level to -1

Currently the init level is set to 0(enabled), but at this point of
time, the actual voltage is not being set yet. If the device boots
up in low temp, it will try to set level to 0(enabled) again. Since
it will check the level against with previous level which is also
0(means enabled), it will not set the actual voltage/frequency for
the rails.

Set the init level to -1(disabled), so that when device defaults to
enable vdd restriction, it will actually set the voltage.

Change-Id: I9997245953c9947889a813901032c3df8c737ad3
Signed-off-by: Jennifer Liu <chihning@codeaurora.org>