Revert "regulator: Enable supply regulator if child rail is enabled."

The change results in the following incorrect behavior.
If a given regulator has a parent supply and the regulator is
enabled either before or during regulator_register(), then
regulator_enable() is called on the supply.  Unfortunately, there
is no matching regulator_disable() call.  This means that the
parent supply will stay enabled forever even if the child is
disabled later.

The stated goal of the change was to enable the parent of a
regulator which was enabled based on its machine constraints.
However, the only constraints that leads to enable() being called
for a regulator are boot-on or always-on.  If these have been
specified for a child regulator then they should have also been
specified for its parent regulator.  Therefore, there should be
no need to explicitly enable the parent when the child is
registered.

Signed-off-by: David Collins <collinsd@codeaurora.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>