[ARM] 3188/1: Add missing i2c dependency for Akita

Patch from Richard Purdie

Akita requires inbuilt kernel i2c support for its GPIOs. Add this
requirement to Kconfig and update the defconfig to match.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>