chromeos for exynos5 (download and build)

- downlaod chromeos kernel

#] git clone https://git.chromium.org/git/chromiumos/third_party/kernel

#] git checkout -b chromeos-3.4 origin/chromeos-3.4

- setup the build environment

#] ./chromeos/scripts/prepareconfig chromeos-exynos5

- build kernel for uImage and dtb

#] make -j8

#] make dtbs

#] make uImage