ARM: ixp4xx: Remove unused debug iomap

If we don't provide the .map_io() callback, the LL debug
defines will kick in anyway, so delete the UART debug map
as well.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20221121221015.1454948-1-linus.walleij@linaro.org


Signed-off-by: Arnd Bergmann <arnd@arndb.de>