spi: Parse hold/inactive CS delay values from the DT

Now that we support parsing the setup time from the Device Tree, we can
also easily support the remaining hold and inactive time delay values.

Signed-off-by: Janne Grunau <j@jannau.net>
Signed-off-by: Hector Martin <marcan@marcan.st>
Link: https://lore.kernel.org/r/20230113102309.18308-4-marcan@marcan.st


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