power-supply: Don't return -EINVAL from __power_supply_find_supply_from_node()

We need to stop 'class_for_each_device' loop when a supply matches with the
of-node. In order to achieve this we currently return -EINVAL from
__power_supply_populate_supplied_from() on successful match.

class_for_each_device() is free to return similar errors in other cases as well
and so the choice of return value here isn't particularly great.

This commit isn't removing the Hack but making it more elegant by returning '1'
instead.

Also power_supply_find_supply_from_node() can return errors other than
-EPROBE_DEFER now if class_for_each_device() fails.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sebastian Reichel <sre@kernel.org>