ARM: dts: omap4: Probe watchdog 3 with ti-sysc

Before updating wdt2 to probe with ti-sysc we want to have wdt3
probed with ti-sysc to avoid having them unnecessarily swap order.

With ti-sysc, we probe child devices at module_init time while
and until l4 abe interconnect is converted to use ti-sysc, wdt3
will probe earlier with legacy platform data.

Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>