thermal: rockchip: don't pass table structs by value

This driver passes struct chip_tsadc_table by value throughout; this is
inefficient, and AFAICT, there is no reason for it. Let's pass pointers
instead.

Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Caesar Wang <wxt@rock-chips.com>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>