CANCTRL_REQOP_CONF
mcp251x_write_reg(spi, CANCTRL, CANCTRL_REQOP_CONF);
ret = mcp251x_read_stat_poll_timeout(spi, value, value == CANCTRL_REQOP_CONF,
ret = mcp251x_read_stat_poll_timeout(spi, value, value == CANCTRL_REQOP_CONF,