ARM: dts: Add max77693 charger node for exynos4412-trats2

Add to Trats2 DTS new node for configuring the max77693 charger driver.
Only the maxim,constant-microvolt differs from default value but set all
of the optional properties anyway.

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