mfd: max8997: Cast void pointer to data of max8997_pmic_dt_match

Casting (void *) data of max8997_pmic_dt_match is necessary,
because variable 'data' of struct 'of_device_id' is defined as
'const void *data'. Thus, pointer should be used instead of value.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>