ARM: dts: msm: remove CX, MX and MMCX always-on configuration for Lahaina

Remove the regulator-always-on configuration flag from VDD_CX,
VDD_MxA, VDD_MxC, and VDD_MMCX regulators.  Also reduce their
minimum allowed operating levels from Turbo to Retention or
LowSVS.

This ensures that these regulators can be scaled down and
disabled in system low power use cases.

Change-Id: I3c3f37cb28fbbb34d5e5bd971669ba4bdda56995