ARM: multi_v7_defconfig: Enable GPIO-based I2C arbitration support

The I2C GPIO arbitration driver is used on the Exynos5250 Snow Chromebook
to arbitrate the access to a I2C bus by the Application Processor or a EC.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>