UPSTREAM: regulator: core: Clear the supply pointer if enabling fails

UPSTREAM: regulator: core: Clear the supply pointer if enabling fails

During the resolution of a regulator's supply, we may attempt to enable
the supply if the regulator itself is already enabled. If enabling the
supply fails, then we will call _regulator_put() for the supply.
However, the pointer to the supply has not been cleared for the
regulator and this will cause a crash if we then unregister the
regulator and attempt to call regulator_put() a second time for the
supply. Fix this by clearing the supply pointer if enabling the supply
after fails when resolving the supply for a regulator.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
(cherry picked from commit 8e5356a73604f53da6a1e0756727cb8f9f7bba17)

Change-Id: I3e83852db8c624fdd5b6c0bcab42c07289501a58
Signed-off-by: David Wu <david.wu@rock-chips.com>