regulator: rk808: Fix missing of_node_put

1. Pass &pdev->dev rather than &client->dev to of_regulator_match, the *dev
   argument is used for devres to ensure devm_of_regulator_put_matches() will
   be called when unload the module.

2. of_get_child_by_name() returns a node pointer with refcount incremented.
   Thus add missing of_node_put(reg_np).

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>