ARM: dts: msm: Add VDDCX supply to HSPHY for MSM8994 and 8992

USB HS PHY drivers need to also vote for this rail, which is
supplied by PM8994 S1 regulator, in order to prevent VDDmin
from happening in some cases, particularly when a charger
is connected.

Change-Id: If3e40316f5d243d19b674c8b635500c514cb9c3b
Signed-off-by: Jack Pham <jackp@codeaurora.org>