spi: cadence: Add SPI transfer delays

When processing an SPI transfer, honor the delay that might be passed
along with it.

Signed-off-by: Daniel Mack <daniel@zonque.org>
Link: https://lore.kernel.org/r/20201009100309.381279-1-daniel@zonque.org


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