ARM: dts: msm: Add the parent supply properties for GDSCs on SDM855

Associate the multimedia GDSCs with their respective parent rails
in order to toggle them along with the GDSCs.

Change-Id: I34dbd09294951ba50edfacd6bbef9576d571a0d2
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>