AM5 IDK boards have TC358778 DPI-to-DSI bridge. Two different DSI panel
models are used with the AM5 IDKs, and these panels are added with DT
overlays. The AM5 IDKs can also be used without any panel.

Add TC358778 data to the am57xx-idk-common.dtsi, but set the status to
disabled.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>