serial: sc16is7xx: remove unused to_sc16is7xx_port macro

This macro is not used anywhere.

Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230905181649.134720-1-hugo@hugovil.com


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