ARM: dts: msm: Add secondary phandles for trinket regulators

Add secondary phandles to the regulator device nodes to resemble
the power grid and hence clients can easily identify their
regulators. Add tertiary phandle for the CX/MX rails. Also modify
the WCSS_CX regulator to voltage based instead of level based.

Change-Id: I900fda9c5072ac3c15607a10ef26938811b74440
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>