ARM: dts: msm: reduce VDD_GFX LowSVS CPR voltage margins for msm8996v2

The VDD_GFX LowSVS corner cannot be used on MSM8996 v2.0, v2.1,
or v3.0 chips.  Therefore, reduce the LowSVS open-loop and
closed-loop voltage margin adjustments to 0 mV so that they
do not artificially raise the SVS voltages after monotonicity is
imposed.

Change-Id: I24579312279424fe30e3b93d42f8b915fe79382e
Signed-off-by: David Collins <collinsd@codeaurora.org>