regulator: core: Use class device list for regulator_list in late init

regulator: core: Use class device list for regulator_list in late init

The regulator_list has exactly the same contents as the list that the
driver core maintains of regulator_class members so is redundant. As a
first step in converting over to use the class device list convert our
iteration in late_initcall() to use the class device iterator.

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