Add documentation for valid use of removeProvider.

    bool isLogicalCameraLocked(const std::string& id, std::vector<std::string>* physicalCameraIds);

    // No method corresponding to the same provider / member belonging to the

    // same provider should be used after this method is called since it'll lead

    // to invalid memory access (especially since this is called by ProviderInfo methods on hal

    // service death).

    status_t removeProvider(const std::string& provider);

    sp<StatusListener> getStatusListener() const;