add FLASH_SIZE_START_ADDR/FLASH_SIZE_END_ADDR for atmega2560
add FLASH_SIZE_START_ADDR/FLASH_SIZE_END_ADDR for atmega2560

paradajz/OpenDeck,paradajz/OpenDeck,paradajz/OpenDeck,paradajz/OpenDeck,paradajz/OpenDeck,paradajz/OpenDeck