ARM: exynos_defconfig: Enable USB Video Class support

The Exynos5420 Peach Pit and Exynos5800 Peach Pi boards have a built-in
Silicon Motion USB UVC WebCam. Enable support for the USB Video Class
driver and its needed media Kconfig symbols so the camera is supported.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>