ARM: dts: Add support for sbc-3xxx with cm-t3730

ARM: dts: Add support for sbc-3xxx with cm-t3730

This adds support for CompuLab SBC-T3530, also known as cm-t3730:

http://compulab.co.il/products/sbcs/sbc-t3530/

It seems that with the sbc-3xxx mainboard is also used on
SBC-T3517 and SBC-T3730 with just a different CPU module:

http://compulab.co.il/products/sbcs/sbc-t3517/
http://compulab.co.il/products/sbcs/sbc-t3730/

So let's add a common omap3-sb-t35.dtsi and then separate SoC
specific omap3-sbc-t3730.dts, omap3-sbc-t3530.dts and
omap3-sbc-t3517.dts.

I've tested this with SBC-T3730 as that's the only one I have.
At least serial, both Ethernet controllers, MMC, and wl12xx WLAN
work.

Note that WLAN seems to be different for SBC-T3530. And SBC-T3517
may need some changes for the EMAC Ethernet if that's used
instead of the smsc911x.

Cc: devicetree@vger.kernel.org
Cc: Mike Rapoport <mike@compulab.co.il>
Acked-by: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Tony Lindgren <tony@atomide.com>