otPlatDiagGpioGetMode() function

OT_ERROR_NONE Successfully got the gpio mode. OT_ERROR_FAILED Mode returned by the platform is not implemented in OpenThread or a platform error occurred while getting the gpio mode. OT_ERROR_INVALID_ARGS @p aGpio is not supported or @p aMode is NULL. OT_ERROR_INVALID_STATE Diagnostic mode was not enabled. OT_ERROR_NOT_IMPLEMENTED This function is not implemented or configured on the platform.