snap: initial addition, Boundary Devices board

snap: use nitrogen6x/ddr-setup.cfg
snap: add CONFIG_CMD_GPIO
snap: use boundary.h
snap: add CONFIG_SPI_FLASH_SPANSION
snap: snap_defconfig add CONFIG_BLOCK_CACHE
snap: use common code for eth init
snap: eth.c now in common directory
snap: move misc_init_r/do_kbd to common
snap: move mmc_init/ dram_init/ overwrite_console/ common_board_init/ splash_screen_prepare/ board_cfb_skip to common
snap: use common 1066mhz_4x256mx16.cfg
snap: add  CONFIG_SPI_FLASH_GIGADEVICE: to defconfigs
snap: use common ddr script
snap: port to v2018.07

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>

snap: update to v2017.01
snap: update to v2017.03

Signed-off-by: Gary Bisson <gary.bisson@boundarydevices.com>