power: smb5: Add die temp to regulate ICL on RST threshold

Currently, die temp does not directly regulate ICL. In case of die temp
fault, it could rush quickly across T_RST threshold to reach T_SHUTDOWN,
and HW shutsdown PMIC, while SW could handle it more gracefully and
effectively by early intervention.

Fix it by reducing ICL to 500mA once die temp hits T_RST threshold.

Change-Id: Icdcd2d88f87af9e44e28a3f362adde90c785ee87
Signed-off-by: Harry Yang <harryy@codeaurora.org>