ARM: dts: msm: Enable dynamic fps rate for 8916 MTP

Add DT property to enable variable refresh rate feature on
JDI 1080p video mode panels on 8916 MTP devices.
This switches the fps of the panel by changing the vertical front
porch region keeping the DSI byte and pixel clock rates constant.

Change-Id: If62a79d88135af90a4da4262309eeed78f3d8f26
Signed-off-by: Raghavendra Ambadas <rambad@codeaurora.org>