arm64: dts: ti: k3-j784s4-main: Add DSS and DP-bridge node

Add DSS and DP-bridge node for J784S4 SoC. DSS IP in J784S4 is
same as DSS IP in J721E, so same compatible is being used.
The DP is Cadence MHDP8546.
Disable them by default as nodes are missing port definition
and phy link configurations which are added later in platform
dt file.

Signed-off-by: Rahul T R <r-ravikumar@ti.com>
[j-choudhary@ti.com: move dss & mhdp node together in main, fix dss node]
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Reviewed-by: Aradhya Bhatia <a-bhatia1@ti.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Link: https://lore.kernel.org/r/20231019054022.175163-4-j-choudhary@ti.com


Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>