bdinfo: Show information about the serial port

bdinfo: Show information about the serial port

It is useful to see the detailed setting of the serial port, e.g. to
allow setting up earlycon or console for Linux. Add this output to the
'bdinfo' command.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
[bmeng: squashed in 20230716033929.253357-2-sjg@chromium.org]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>