drivers: thermal: Initialize thermal core earlier

Modern devices have two contradictory boot requirements - boot as
quickly as possible (which often means runs as fast as possible) while
staying under the thermal envelope.

Now that we've moved cpufreq initialisation and supported platform
drivers to core_initcall, let us move the thermal framework
initialization earlier too.

However, netlink initialization happens only as part of fs_initcall so
it has a userspace available. Initialize netlink events separately,
later in the boot process.

Originally-by: Lina Iyer <ilina@codeaurora.org>
Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Ondrej Kubik <ondrej.kubik@canonical.com>