ARM: dts: Add Maxim 77693 fuel gauge node for exynos4412-trats2

Add node for fuel gauge present in Maxim 77693 PMIC. This allows control
over battery charging state on Trats2 board.

The fuel gauge is compatible with max17042 battery driver (Maxim
17042/17047/17050).  Although datasheet rev 2.2 for MAX77693 describes
fuel gauge as Maxim 17042-like, the chip on Trats2 board identifies
itself as Maxim 17047-like.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>