This adds the grf property to handle the tsadc power sequence on
rockchip some SoCs.

Verified on rk3399 can work with this patch on now.

while true; do grep "" /sys/class/thermal/thermal_zone[0-1]/temp
sleep .5; done
/sys/class/thermal/thermal_zone0/temp:40555
/sys/class/thermal/thermal_zone1/temp:41111
/sys/class/thermal/thermal_zone0/temp:40555
/sys/class/thermal/thermal_zone1/temp:41111
/sys/class/thermal/thermal_zone0/temp:40555
/sys/class/thermal/thermal_zone1/temp:41666
/sys/class/thermal/thermal_zone0/temp:40555
/sys/class/thermal/thermal_zone1/temp:41111
/sys/class/thermal/thermal_zone0/temp:40555
/sys/class/thermal/thermal_zone1/temp:41111
/sys/class/thermal/thermal_zone0/temp:40555
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>