ARM: dts: am33xx: add remaining PRM instances

Add remaining PRM instances for the am33xx SoC. Additionally, enable the
genpd support for them.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
[tony@atomide.com: fixed a typo for #power-domain-cells]
Signed-off-by: Tony Lindgren <tony@atomide.com>