arm64: dts: ti: am65x: Fix dtbs_install for Rocktech OLDI overlay

Add the overlay dtbo file to a Makefile target so it can be
picked by the dtbs_install command.

Fixes: b8690ed3 ("arm64: dts: ti: am65x: Add Rocktech OLDI panel DT overlay")
Signed-off-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Aradhya Bhatia <a-bhatia1@ti.com>
Link: https://lore.kernel.org/r/20240208-for-v6-9-am65-overlays-2-0-v2-1-70bae3e91597@kernel.org


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