red-brick: Add basic board config
sunxi: If SPL_OS_BOOT if set but AXP209_POWER is not set boot to Linux

Before there was no spl_start_uboot() in the sunxi board.c under this
conditions and the code fell back to loading u-boot.
red-brick: Disable AXP and I2C support
red-brick: Switch serial console to UART3
red-brick: Read script.bin directly from MMC0 into RAM
red-brick: Move kernel offset on MMC0 from 1600 to 224

Also disable reading raw-mode arguments from MMC0 as this is not used.