ARM: dts: msm8974: add display support

Add the MDP5, DSI and DSI PHY blocks for the display found on the
msm8974 SoCs. This is based on work from msm8916.dtsi and Jonathan
Marek.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>