mfd: max77693: Added device tree support

This patch adds only of_match_table. There are no device specific
properties.

Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>