ARM: dts: Add suspend configuration for max77686 regulators for exynos4412-trats2

Add suspend to RAM configuration for max77686 regulators. Some LDOs
and bucks are disabled. This reduces energy consumption during S2R,
approximately from 17 mA to 9 mA.

Additionally remove old and not supported bindings:
 - regulator-mem-off
 - regulator-mem-idle
 - regulator-mem-on
The max77686 driver does not parse them and they are not documented
anywere.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>