ARM: davinci: add support for am1808 based EnBW CMC board

ARM: davinci: add support for am1808 based EnBW CMC board

This board supports:

- AM1808 based board
- 64 MiB DDR ram
- 2 MiB Nor flash
- 128 MiB NAND flash
- use internal RTC
- I2C support
- hwmon lm75 support
- UBI/UBIFS support
- MMC support
- USB OTG support

This patch adds the basic DTS file enabling the serial ports.
Other features will be added in due course of time.

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: linux-arm-kernel@lists.infradead.org
Cc: devicetree-discuss@lists.ozlabs.org
Cc: davinci-linux-open-source@linux.davincidsp.com
Cc: Sekhar Nori <nsekhar@ti.com>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Wolfgang Denk <wd@denx.de>
[nsekhar@ti.com: modified after dtsi refactoring and added binding
documentation]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>