serial: clean up uart_info

Since commit ebd2c8f6 ("serial: kill off uart_info") has
removed uart_info, the uart_info declaration looks lonely,
let it go.

Signed-off-by: Yanteng Si <siyanteng@cqsoftware.com.cn>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240920053423.1373354-1-siyanteng@cqsoftware.com.cn


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>