arm: dts: k3-am654-r5-base-board: enable wkup_vtm0 node and link in supplies

Link the vdd-supplies for the voltage domains under the VTM node. Also,
enable the node under SPL. This will enable the AVS class 0 support on
am65x-evm board.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Keerthy <j-keerthy@ti.com>