spi: mt65xx: Convert to GPIO descriptors

The MT65xx driver was already relying on the core to get some
GPIO line numbers so it can be (hopefully) trivially converted
to use descriptors instead.

Cc: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Cc: Mason Zhang <Mason.Zhang@mediatek.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Peter Hess <peter.hess@ph-home.de>
Cc: Leilk Liu <leilk.liu@mediatek.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220122003302.374304-1-linus.walleij@linaro.org


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