ARM: dts: Configure omap4 and 5 l4_abe for genpd and drop platform data

We can power off l4_abe domain when not in use when we configure it for
genpd. And with that change, we can now also drop the old unused legacy
platform data.

Note that we also need to now use "simple-pm-bus" instead of "simple-bus"
for PM runtime to get enabled for the bus.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>