ARM: dts: am335x-phycore: switch to new cpsw switch drv

The dual_mac mode has been preserved the same way between legacy and new
driver, and one port devices works the same as 1 dual_mac port - it's safe
to switch drivers.

So, switch Phytec AM335x phyCORE SOM, phyBOARD-WEGA, phyBOARD-REGOR,
PCM-953 to use new cpsw switch driver. Those boards have or 2 Ext. port
wired and configured in dual_mac mode by default, or only 1 Ext. port.

Cc: Teresa Remmet <t.remmet@phytec.de>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>