ARM: dts: msm: add the DSI PLL clocks to MDSS DSI nodes for msmtitanium

Add the DT entries for main and shadow DSI PLL clocks to the respective
MDSS DSI nodes for msmtitanium target. This is needed to switch the
frequency of DSI PLL whenever needed as part of dynamic FPS feature.

Change-Id: I5546146eba0cdfab24b06ae2407fdbe14f1b631b
Signed-off-by: Padmanabhan Komanduru <pkomandu@codeaurora.org>