ARM: dts: msm: remove unused DSI PHY timing setting for SM8150

The DSI PHY clockout timing parameters are not configured using the
t-clk-pre and t-clk-post parameters for SM8150. Remove these bindings
from all supported displays on SM8150.

Change-Id: I8ee1c665ea845b9a6cdc4acf89309960445c98ff
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>