ARM: dts: Add minimal DT support for DevKit8000

DevKit8000 is a beagle board clone from Timll, sold by
armkits.com. The DevKit8000 has RS232 serial port, LCD, DVI-D,
S-Video, Ethernet, SD/MMC, keyboard, camera, SPI, I2C, USB and
JTAG interface.

Add the basic DT support for devkit8000. It includes:
- twl4030 (PMIC)
- MMC1
- I2C1
- leds

Signed-off-by: Anil Kumar <anilk4.v@gmail.com>
Tested-by: Thomas Weber <thomas@tomweber.eu>
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>