ARM: dts: sb-t35: fix Ethernet power supply

SB-T35 baseboard features SMSC9220 Ethernet chip which requires
its own power supply regulators.

Add baseboard specific regulators for the SB-T35 Ethernet chip.

Signed-off-by: Dmitry Lifshitz <lifshitz@compulab.co.il>
Signed-off-by: Tony Lindgren <tony@atomide.com>