ARM: dts: Add VAR-SOM-OM44 WLAN nodes

Both the VAR-STK-OM44 and VAR-DVK-OM44 boards comes with the
WLAN/BT version of the system on module VAR-SOM-OM44.

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>