ARM: dts: msm: Change CPR down threshold for msm8939

The current VDD_APC CPR down thresdhold value of 2 makes the
CPR controller too sensitive to voltage ripple in the VDD_APC
supply. This results in the CPR UP and DOWN interrupts firing
repeatedly in an alternating fashion.

Change the CPR down threshold to 3 in order to eliminate the
undesirable CPR interrupt behavior.

CRs-Fixed: 704662
Change-Id: I765dcd9b91a55f81a557c874ff457ee25c9d49fe
Signed-off-by: Tirupathi Reddy <tirupath@codeaurora.org>