regulator: arizona-micsupp: Avoid potential memory leak reading init_data

The device argument passed to of_get_regulator_init_data is used to
do some devres memory allocation. Currently the driver passes the MFD
device pointer to this function, this could result in the init_data
allocation being leaked if the regulator is unbound but the MFD isn't.

Correct this issue by correctly passing the local platform device.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>