spi: st-ssc4: Covert to use GPIO descriptors

This switches the ST SSC SPI controller to use GPIO
descriptors from the core instead of GPIO numbers.
It is already using the core parsing of GPIO numbers
so the switch is pretty straight-forward.

Cc: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20220201012654.562578-1-linus.walleij@linaro.org


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