ARM: dts: msm: Update CPR SW settings for msm8939

MSM8939 has CPR for controlling voltage on VDD_APC.
Also, VDD_APC is supplied from external buck regulator.
Update voltage step_size and CPR step_quotient values
according to external buck regulator in use.

Change-Id: I31af6c26a3d1e54da5cc89f1e663d2f85f604cd9
Signed-off-by: Tirupathi Reddy <tirupath@codeaurora.org>