serial: sc16is7xx: simplify to_sc16is7xx_one() with a single parameter

serial: sc16is7xx: simplify to_sc16is7xx_one() with a single parameter

Simplify macro to_sc16is7xx_one() to only take one parameter, as most
of the time (19) it is called with the "port" structure name. This
improves readability.

For the remaining places where it is called (4), simply use container_of()
locally. This is similar to what is done in other drivers (ex: max310x).
For sc16is7xx_tx_proc(), first assigning "one" variable allows to simplify
"port" variable init.

Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://patch.msgid.link/20251027142957.1032073-10-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>