ARM: dts: msm: Update and enable the clock_dispcc node on SDM855

Update the device tree node for clock_dispcc to move from using
dummy clocks to actually programming the clock registers as per
client requests.

Change-Id: I3cdedc713d43b0ab520a5520da8107e952b8f2fb
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>