MXS-2304 Remove config_get_param()

Replaced with other functions. Also removed password deprecation check.

server/core/internal/config.hh

@@ -253,12 +253,3 @@ void dump_param_list(int file,
  * @return True if the parameter can be modified at runtime
  */
 bool config_can_modify_at_runtime(const char* name);
-
-/**
- * @brief Get a configuration parameter
- *
- * @param params List of parameters
- * @param name Name of parameter to get
- * @return The parameter or NULL if the parameter was not found
- */
-MXS_CONFIG_PARAMETER* config_get_param(MXS_CONFIG_PARAMETER* params, const char* name);