spi: ath79: switch to use modern name

Change legacy name master/slave to modern name host/target or controller.

No functional changed.

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20221230092806.1687340-2-yangyingliang@huawei.com


Signed-off-by: Mark Brown <broonie@kernel.org>