ARM: dts: Add omap3-beagle.dts

Add a minimal dts for original OMAP3430/3530 version of the Beagle board. This
version of the Beagle board has 256MB of DDR and features the same TWL4030
power management IC (PMIC) as the Beagle board XM.

Given that the Beagle and Beagle-XM boards use the same PMIC, move the
definition of the VSIM regulator into the TWL4030.dtsi file so that we do not
need to duplicate in the Beagle board dts file.

This has been boot tested on an OMAP3530 Beagle board and verifing that the
SD/MMC interface is working with a SD card.

V2 changes
- Rebased upon of devel-dt
- Corrected copyright date in omap3-beagle.dts file
- Added LED support after verifing that Beagle and Beagle XM have the same LED
  configuration

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Signed-off-by: Benoit Cousson <b-cousson@ti.com>