rtc: max77686: avoid reference of parent device info multiple places

Get rid of referring parent device info for register access
all the places by making regmap as part of max77686 rtc
device info. This will also remove the need of storing parent
device info in max77686 rtc device info as this is no more required.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Tested-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Tested-by: Javier Martinez Canillas <javier@osg.samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>