coreboot: Add snow chromebook configs

This adds coreboot configuration for the Samsung Chromebook - XE303,
which is based on the "google/daisy" mainboard in upstream coreboot.
Also adds a shared "daisy" board directory to share with others having
the same baseboard.

The config is based on the following defconfig:

    CONFIG_VENDOR_GOOGLE=y
    CONFIG_CBFS_SIZE=0x00400000
    CONFIG_UART_FOR_CONSOLE=3
    CONFIG_BOARD_GOOGLE_DAISY=y
    CONFIG_CONSOLE_CBMEM_BUFFER_SIZE=0x20000
    CONFIG_EC_GOOGLE_CHROMEEC_I2C_BUS=0x4
    CONFIG_UART_PCI_ADDR=0x0
    CONFIG_I2C_TRANSFER_TIMEOUT_US=500000

Untested since I don't have the snow chromebook. This also fails without
a non-free 3rdparty/blobs/cpu/samsung/exynos5250/bl1.bin blob.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>