arm64: dts: ti: am65-wakeup: Add VTM node

VTM stands for voltage and thermal management.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Tero Kristo <t-kristo@ti.com>