ARM: multi_v7_defconfig: Make MAX77802 regulator driver built-in

Maxim 77802 PMIC is a main PMIC for the following Exynos5 based boards:
Odroid XU, Chromebook Pit and Chromebook Pi. Driver for its voltage
regulator is needed very early during boot to properly instantiate SD/MMC
devices and mount rootfs, so change that driver to be compiled-in.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>