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>

drivers/regulator/core.c

@@ -1536,6 +1536,7 @@ static int regulator_resolve_supply(struct regulator_dev *rdev)
 		ret = regulator_enable(rdev->supply);
 		if (ret < 0) {
 			_regulator_put(rdev->supply);
+			rdev->supply = NULL;
 			return ret;
 		}
 	}