ARM: dts: da850: Add basic DTS for the LCDK

The LCDK is the successor to the late Hawkboard.
Among the differences are the flash (16bits vs 8bits) and some pins
(MMC, LEDs, buttons, some external connectors), however the main
components remain the same (eth. phy, audio codec, video decoder and
DAC) except for the main PMIC, different and hard-wired on the LCDK (the
LDOs and DCDCs are always on).
A DT-only boot with this addition gives functional UART, reboot via
watchdog, RTC, ethernet and MMC (I added the CD GPIO for the MMC
although davinci_mmc doesn't call the OF facilities of mmc core).

Cc: Sekhar Nori <nsekhar@ti.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Karl Beldan <kbeldan@baylibre.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>