regulator: devres: unexport devm_regulator_unregister_supply_alias()

This API hook isn't used anywhere outside of the regulator devres code.
This function is needed for the devm_regulator_bulk_register_supply_alias()
function on the error path, to cleanup any previously registered supply
aliases.

This change makes the devm_regulator_unregister_supply_alias() local to the
regulator core framework, to avoid it being used in any weird logic.
It's also removing the doc-string for
devm_regulator_unregister_supply_alias(), since it doesn't need to be
documented anymore, as no other external consumer should use it.

Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
Link: https://lore.kernel.org/r/20210625122324.327585-5-aardelean@deviqon.com


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