ARM: dts: msm: Add vdd restriction support for msm8226

Enable the vdd restriction feature for VDD_DIG and VDD_APPS when low
temperature condition happens on msm8226. Specify the low
temperature thresholds and add the voltage rails information. Voltage
floor will be set when threshold is crossed, and voltage floor will
be cleared when threshold hysteresis is crossed.

Change-Id: I281d92dea90a1f1b20a30c1b02b2c765e8d8d737
Signed-off-by: Jennifer Liu <chihning@codeaurora.org>