ARM: multi_v7_defconfig: fix failure setting CPU voltage by enabling dependent I2C controller

This patch fixes a long standing issue introduced during the 3.16 merge window.
Shortly after the merge, exynos5250-based arndale boards began to produce the
following errors:

kern.err kernel:  exynos-cpufreq exynos-cpufreq: failed to set cpu voltage
kern.err kernel:  cpufreq: __target_index: Failed to change cpu frequency: -22

Further analysis revealed that the S5M8767 voltage regulator used on the
exynos5250-based arndale board utilizes the S3C2410 I2C controller. If the
S3C2410 I2C controller driver is not enabled, the S5M8767 voltage regulator
fails to probe. Therefore a dependency exists between these two drivers.
In the exynos_defconfig both CONFIG_REGULATOR_S5M8767 and CONFIG_I2C_S3C2410
options are enabled, and no errors are produced. However, in the
multi_v7_defconfig only the CONFIG_REGULATOR_S5M8767 option is enabled and the
errors are present. So let's enable the CONFIG_I2C_S3C2410 option in the
multi_v7_defconfig to allow the S5M8767 voltage regulator to probe.

Signed-off-by: Tyler Baker <tyler.baker@linaro.org>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>