ARM: dts: msm: Use voltage floor corner for PM8110 SMPS 1 on msm8610

Add a voltage floor corner regulator interface in the MSM8610
device tree for the PM8110 SMPS 1 regulator (VDD_CX). This
interface will be used to impose a minimum active voltage corner
in low temperature situations.

Change-Id: I26d833ac8184576285ce992d7a7c6fd9dc1b3cbd
Signed-off-by: Jennifer Liu <chihning@codeaurora.org>