arm: dts: ti: omap: omap36xx: Rename opp_supply nodename

Use opp-supply as the proper node name.

Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Message-ID: <20230724153911.1376830-2-nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>