ARM: exynos_defconfig: Enable DWC2 USB driver and USB ethernet gadget

DWC2 (s3c-hsotg) hardware module is available on many Exynos based boards,
so enable DWC2 driver as well as the most common USB Ethernet gadget.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>