iio: st_sensors: core and lsm9ds0 switch to devm_regulator_bulk_get_enable()

iio: st_sensors: core and lsm9ds0 switch to devm_regulator_bulk_get_enable()

These drivers only turns the power on at probe and off via a custom
devm_add_action_or_reset() callback. The two regulators were handled
separately so also switch to bulk registration.
The new devm_regulator_bulk_get_enable() replaces all this boilerplate
code.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20221016163409.320197-8-jic23@kernel.org