arm64: dts: ti: k3-am625-sk: Add epwm nodes

Add epwm nodes and mark them disabled, as they're
not currently in use.

Signed-off-by: Georgi Vlaev <g-vlaev@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20220531205229.198011-3-g-vlaev@ti.com