Fix erroneous object name

Author: Redande

app/controllers/api/v8/users_controller.rb

@@ -294,7 +294,7 @@ def set_password
         def maybe_update_password
           if params[:old_password].present? && params[:password].present?
             if @user.password_managed_by_courses_mooc_fi && @user.courses_mooc_fi_user_id.present?
-              return @user.update_password_via_courses_mooc_fi(user_params[:old_password], user_params[:password])
+              return @user.update_password_via_courses_mooc_fi(params[:old_password], params[:password])
             end
             if !@user.has_password?(params[:old_password])
               @user.errors.add(:old_password, 'incorrect')