ARM: omap2plus_defconfig: Update for moved DSI command mode panel

The DSI command mode panel is no longer specific
to OMAP and thus the config option has been renamed
slightly.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201215104657.802264-50-tomi.valkeinen@ti.com