arm: Add support for LEGO MINDSTORMS EV3

This is based on the davinci da850evm. It can boot from either the
on-board 16MB flash or from a microSD card. It also reads board
information from an I2C EEPROM.

The EV3 itself initally boots from write-protected EEPROM, so no
u-boot SPL is needed.

Signed-off-by: David Lechner <david@lechnology.com>
Reviewed-by: Tom Rini <trini@konsulko.com>