ARM: OMAP2+: Drop legacy platform data for dm814x cpsw

We can now probe devices with ti-sysc interconnect driver and dts
data. Let's drop the related platform data.
dts property.

Cc: Graeme Smecher <gsmecher@threespeedlogic.com>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>