regulator: core: Release regulator-regulator supplies on error

commit e81dba85c6388dfabcb76cbc2b8bd02836a53ae5 upstream.

If we fail while registering a regulator make sure we release the supply
for the regulator if there is one.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>