U-Boot v2016.05 for Arduino Tre - release 2

• Improve Arduino Tre default configuration file
• Add the functions "arduinotre_add_board_info()" and
  "arduinotre_virtual_eeprom_get" to manage Arduino Tre info
  instead of using CONFIG_TREBOARD
• Added little improvements to U-Boot configuration for Arduino Tre

U-Boot v2016.05 for Arduino Tre - release 1

• Add support for Arduino Tre in U-Boot source tree based on TI am335x
• Add SDRAM DDR3 definitions for Arduino Tre
• Add Arduino Tre board specific code for hardware initialization
• Add Arduino Tre default configuration files named
  'am335x_arduinotre_defconfig'
• Add initial configuration to get Arduino Tre board info to avoid
  reading from EEPROM because, unlike many TI AM335X-based platforms,
  Arduino Tre doesn't have an EEPROM used to get board info
• Add README file for info about Arduino Tre and building instructions