ARM: dts: msm: configure APC supply regulator S2 to auto mode for msm8610

Configure PMIC PM8110 regulator SMPS 2 for auto mode.  When
operating in auto mode, the regulator automatically switches
between PWM (high power) and PFM (low power) modes based upon
real-time current consumption.  This results in lower aggregate
power consumption since PFM mode has lower ground current than
PWM mode.

Change-Id: Iddd7a1303235cf7fdd8235b88e47c46b7be615ad
Signed-off-by: David Collins <collinsd@codeaurora.org>