revive: the default config is only applied when no dedicated config

[ldez]

Fix #1770

#1770 (comment)

The code from revive:

// GetConfig yields the configuration
func GetConfig(configPath string) (*lint.Config, error) {
	config := defaultConfig()
	if configPath != "" {
		var err error
		config, err = parseConfig(configPath)
		if err != nil {
			return nil, err
		}
	}
	normalizeConfig(config)
	return config, nil
}

The same thing in this PR:

func getReviveConfig(cfg *config.ReviveSettings) (*lint.Config, error) {
	conf := defaultConfig()

	if !reflect.DeepEqual(cfg, &config.ReviveSettings{}) {
		rawRoot := createConfigMap(cfg)
		buf := bytes.NewBuffer(nil)

		err := toml.NewEncoder(buf).Encode(rawRoot)
		if err != nil {
			return nil, err
		}

		conf = &lint.Config{}
		_, err = toml.DecodeReader(buf, conf)
		if err != nil {
			return nil, err
		}
	}

	normalizeConfig(conf)

[ernado]

LGTM