iio: accel: bma400: Use devm_regulator_bulk_get_enable()

This driver only turns the power on at probe and off via a custom
devm_add_action_or_reset() callback. The new
devm_regulator_bulk_get_enable() replaces this boilerplate code.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jagath Jog J <jagathjog1996@gmail.com>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/20221016163409.320197-3-jic23@kernel.org