iio: gyro: bmg160_core: Simplify using devm_regulator_*get_enable()

Use devm_regulator_bulk_get_enable() instead of open coded bulk-get,
bulk-enable, add-action-to-disable-at-detach - pattern.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/3fd11489356b1c73a3d7b4bd9dec7e12c9fe8788.1660934107.git.mazziesaccount@gmail.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>