ARM: dts: msm: specify PM8994 S11 regulator 150 mV max step for msm8996

Specify a maximum single voltage step size of 150 mV for the
PM8994 S11 regulator on msm8996 boards.  This regulator powers
the VDD_APCC supply for the application processor clusters.
This stepping limit is needed to ensure that the PLL droop
detector operates properly.  This detector recalibrates when
a new voltage is programmed for VDD_APCC.  The VDD_APCC voltage
must be stable when the recalibration completes so indivdual
changes in voltage must be limited to at most 150 mV.

Change-Id: I2a318e77e86f11cc3b5f9c3963d92a57ed2c38a3
Signed-off-by: David Collins <collinsd@codeaurora.org>