ARM: dts: msm: Use voltage floor corner for PM8019 L10 on msm9625

Add a voltage floor corner regulator interface in the MSM9625
device tree for the PM8019 L10 regulator (VDD_CX).  This
interface will be used to impose a minimum active voltage corner
in low temperature situations.

CRs-Fixed: 507816
Change-Id: I29e9d5bcad87fddaf823507dba0049c77a8a75e3
Signed-off-by: Jennifer Liu <chihning@codeaurora.org>