ARM: dts: msm: Change thermal-mitigation levels for QRD670 device

QRD670 device has a battery can support 4.2A charging current at max, so
change the thermal-mitigation levels to match with the max allowed
charging current.

Change-Id: Ifab1e92222c5df384569a4d6c86f48ed59adb3b6
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>