mips: Add support for SoM "VoCore2".

Small patch to add support for VoCore/VoCore2 board.

VoCore is open hardware and runs OpenWrt/LEDE.
It has WIFI, USB, UART, 20+ GPIOs but is only one inch square.
It will help you to make a smart house, study embedded system
or even make the tiniest router in the world.

Details about this SoM can be found at "https://vocore.io/v2.html".

Signed-off-by: Mauro Condarelli <mc5686@mclink.it>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/configs/vocore2_defconfig b/configs/vocore2_defconfig
new file mode 100644
index 0000000..6cacec0
--- /dev/null
+++ b/configs/vocore2_defconfig
@@ -0,0 +1,101 @@
+CONFIG_MIPS=y
+CONFIG_SPL_LIBCOMMON_SUPPORT=y
+CONFIG_SPL_LIBGENERIC_SUPPORT=y
+CONFIG_ENV_SIZE=0x1000
+CONFIG_ENV_OFFSET=0x04e000
+CONFIG_ENV_SECT_SIZE=0x1000
+CONFIG_SYS_BOOTCOUNT_ADDR=0xb000006c
+CONFIG_SPL_SYS_MALLOC_F_LEN=0x20000
+CONFIG_NR_DRAM_BANKS=1
+CONFIG_SPL=y
+CONFIG_SYS_BOOTCOUNT_SINGLEWORD=y
+CONFIG_ARCH_MTMIPS=y
+CONFIG_BOARD_VOCORE2=y
+CONFIG_RESTORE_EXCEPTION_VECTOR_BASE=y
+CONFIG_MIPS_BOOT_FDT=y
+CONFIG_ENV_VARS_UBOOT_CONFIG=y
+CONFIG_SYS_BOOT_GET_CMDLINE=y
+CONFIG_SYS_BOOT_GET_KBD=y
+CONFIG_FIT=y
+CONFIG_FIT_SIGNATURE=y
+CONFIG_LEGACY_IMAGE_FORMAT=y
+CONFIG_OF_STDOUT_VIA_ALIAS=y
+CONFIG_LOGLEVEL=8
+CONFIG_VERSION_VARIABLE=y
+# CONFIG_DISPLAY_BOARDINFO is not set
+CONFIG_DISPLAY_BOARDINFO_LATE=y
+CONFIG_SPL_SYS_MALLOC_SIMPLE=y
+CONFIG_SPL_NOR_SUPPORT=y
+CONFIG_HUSH_PARSER=y
+CONFIG_CMD_LICENSE=y
+# CONFIG_BOOTM_NETBSD is not set
+# CONFIG_BOOTM_PLAN9 is not set
+# CONFIG_BOOTM_RTEMS is not set
+# CONFIG_BOOTM_VXWORKS is not set
+# CONFIG_CMD_ELF is not set
+# CONFIG_CMD_XIMG is not set
+# CONFIG_CMD_CRC32 is not set
+CONFIG_CMD_MEMINFO=y
+# CONFIG_CMD_FLASH is not set
+CONFIG_CMD_GPIO=y
+CONFIG_CMD_GPT=y
+CONFIG_CMD_GPT_RENAME=y
+# CONFIG_CMD_LOADS is not set
+CONFIG_CMD_MMC=y
+CONFIG_CMD_MTD=y
+CONFIG_CMD_PART=y
+CONFIG_CMD_SPI=y
+CONFIG_CMD_USB=y
+CONFIG_CMD_WDT=y
+CONFIG_CMD_DHCP=y
+CONFIG_CMD_MII=y
+CONFIG_CMD_PING=y
+CONFIG_CMD_BOOTCOUNT=y
+CONFIG_CMD_TIME=y
+CONFIG_CMD_FAT=y
+CONFIG_CMD_FS_GENERIC=y
+CONFIG_CMD_MTDPARTS=y
+CONFIG_MTDIDS_DEFAULT="nor0=spi0.0"
+CONFIG_MTDPARTS_DEFAULT="spi0.0:312k(u-boot),4k(env),4k(factory),2368k(kernel),-(filesystem)"
+CONFIG_DEFAULT_DEVICE_TREE="vocore_vocore2"
+CONFIG_ENV_IS_IN_SPI_FLASH=y
+CONFIG_SYS_RELOC_GD_ENV_ADDR=y
+CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG=y
+CONFIG_NET_RANDOM_ETHADDR=y
+CONFIG_SPL_DM=y
+# CONFIG_DM_DEVICE_REMOVE is not set
+CONFIG_BOOTCOUNT_LIMIT=y
+CONFIG_LED=y
+CONFIG_LED_BLINK=y
+CONFIG_LED_GPIO=y
+CONFIG_MMC=y
+CONFIG_DM_MMC=y
+# CONFIG_MMC_HW_PARTITIONING is not set
+CONFIG_MMC_MTK=y
+CONFIG_MTD=y
+CONFIG_SPI_FLASH_SFDP_SUPPORT=y
+CONFIG_SPI_FLASH_GIGADEVICE=y
+CONFIG_SPI_FLASH_MACRONIX=y
+CONFIG_SPI_FLASH_SPANSION=y
+CONFIG_SPI_FLASH_STMICRO=y
+CONFIG_SPI_FLASH_WINBOND=y
+CONFIG_SPI_FLASH_MTD=y
+CONFIG_MT7628_ETH=y
+CONFIG_PHY=y
+CONFIG_MT76X8_USB_PHY=y
+CONFIG_SPECIFY_CONSOLE_INDEX=y
+CONFIG_CONS_INDEX=3
+CONFIG_SPI=y
+CONFIG_MT7621_SPI=y
+CONFIG_USB=y
+CONFIG_DM_USB=y
+CONFIG_USB_EHCI_HCD=y
+CONFIG_USB_EHCI_GENERIC=y
+CONFIG_USB_STORAGE=y
+CONFIG_WDT=y
+CONFIG_WDT_MT7621=y
+CONFIG_FS_EXT4=y
+CONFIG_FAT_WRITE=y
+CONFIG_LZMA=y
+CONFIG_LZO=y
+CONFIG_SPL_LZMA=y