thermal/drivers/hisi: Put platform code together

Reorganize the code for next patches by moving the functions upper in
the file which will prevent a forward declaration. There is no functional
change here.

Signed-off-by: Kevin Wangtao <kevin.wangtao@linaro.org>
Tested-by: Daniel Lezcano <daniel.lezcano@linaro.org> # hikey6220
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>