tty: serial: 8250: Modify MOXA enum name within 8250_pci.c

To improve clarity, modify the MOXA enum name within pci_board_num_t.

Signed-off-by: Crescent CY Hsieh <crescentcy.hsieh@moxa.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20231018091739.10125-2-crescentcy.hsieh@moxa.com


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