regulator: provide regulator_bulk_set_supply_names()

There are many regulator consumers who - before using the regulator
bulk functions - set the supply names in regulator_bulk_data using
a for loop.

Let's provide a simple helper in the consumer API that allows users
to do the same with a single function call.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Link: https://lore.kernel.org/r/20190830071740.4267-2-brgl@bgdev.pl


Signed-off-by: Mark Brown <broonie@kernel.org>