regulator: core: Provide managed regulator registration

Many regulator drivers have a remove function that consists solely of
calling regulator_unregister() so provide a devm_regulator_register()
in order to allow this repeated code to be removed and help eliminate
error handling code.

Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
index fcb34a5..3d9c2a7 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -283,6 +283,7 @@
   devm_regulator_get()
   devm_regulator_put()
   devm_regulator_bulk_get()
+  devm_regulator_register()
 
 CLOCK
   devm_clk_get()