regulator: core: Use devres for releasing of_regulator_match of_nodes

Rather than requiring individual drivers to put the of_nodes returned
from of_regulator_match use devres to put them. This also has the
benefit it makes the life-time of the of_nodes match the lifetime of
the init data also contained in the of_regulator_match structure, which
seems more consistent.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@linaro.org>