ARM: dts: msm: Add GDSC regulator references for Lahaina's SMMUs

Add references for the GDSC regulators for the APPS and GFX SMMU
devices on Lahaina, to allow the HLOS to vote for these
regulators prior to accessing the respective register spaces.

Change-Id: I6ec4049cd0c17804c3de038f7a821e907d47d3a2