serial: 8250_omap: use uart_port pointer when available

There are unnecessary "up->port." accesses on many places in 8250_omap.
"port" is avalable on most places, so instead simply use "port->".

And make port available in omap8250_restore_regs() too. It's used on
many places in there.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250611100319.186924-34-jirislaby@kernel.org


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