ARM: exynos_defconfig: Update exynos_defconfig

Removed outdated configs. Enabled most of the configs used on latest
Exynos based platforms. This will provide a reference for users trying
to verify and test various features on Exynos based platforms and also
help in detecting breakages by widening the build coverage.

Signed-off-by: Sachin Kamat <sachin.kamat@samsung.com>
[arun.kk@samsung.com: on Snow, Pit, Pi chromebooks]
Tested-by: Arun Kumar K <arun.kk@samsung.com>
Tested-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

Signed-off-by: Olof Johansson <olof@lixom.net>