mfd: max14577: Use module_init() instead of subsys_initcall()

The driver's init function is called at subsys init call level but the
dependencies provided by the driver are looked up by drivers that have
probe deferral support, so manual ordering of init calls isn't needed.

Suggested-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>