ARM: exynos_defconfig: enable HS-I2C to fix for mmc partition mount

High speed I2C is used on Exynos5 based SoCs. Enable it.

The MMC partition for Root filesystem cannot be mounted
without this enabling HS-I2C and regulators on many boards
are connected HS-I2C bus so the regulators don't come by
default without this.

Actually, we are not able to get arndale-octa board to boot
and mount an MMC partition without this change.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Tested-by: Javi Merino <javi.merino@arm.com>
[kgene.kim@samsung.com: modified description]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>