thermal: tegra: add hw-throttle function

Tegra soctherm support HW throttle, when the soctherm snesors'
temperature is above the throttle trip point, it will trigger
pulse skiper to tune clocks accroding to the throttle depth.
Add this function for Tegra124 and Tegra210.
Since Tegra132 use different registers to configure pulse skiper,
will support it in next patch.

Signed-off-by: Wei Ni <wni@nvidia.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>