thermal: Initialize thermal subsystem earlier

Now that the thermal framework is built-in, in order to facilitate
thermal mitigation as early as possible in the boot cycle, move the
thermal framework initialization to core_initcall.

Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/f8ff0ab4a8e9c2eca5a26fb2256365b26cb326ce.1571656015.git.amit.kucheria@linaro.org