ARM: dts: Add missing onewire node for omap4

On omap4 we're missing the onewire node with it's related "ti,hwmods"
property that the SoC interconnect code needs.

Note that this will only show up as a bug with "doesn't have
mpu register target base" boot errors when the legacy platform
data is removed.

Signed-off-by: Tony Lindgren <tony@atomide.com>