thermal/drivers/core: Remove depends on THERMAL in Kconfig

The dependency on the THERMAL option to be set is already there implicitly
by the "if THERMAL" conditionnal option. The sub Kconfigs do not have to
check against the THERMAL option as they are called from a Kconfig block
which is enabled by the conditionnal option.

Remove the useless "depends on THERMAL" in the Kconfigs.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>