spi: dt-bindings: Rename spi-cs-setup-ns to spi-cs-setup-delay-ns

Other delay values follow the delay-ns naming convention, so unify the
newly introduced spi-cs-setup-ns property for consistency.

Also fix a typo while we're here.

Fixes: f6c911f3 ("spi: dt-bindings: Introduce spi-cs-setup-ns property")
Signed-off-by: Hector Martin <marcan@marcan.st>
Link: https://lore.kernel.org/r/20230104093631.15611-2-marcan@marcan.stSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml

@@ -44,9 +44,9 @@ properties:
     description:
       Maximum SPI clocking speed of the device in Hz.
 
-  spi-cs-setup-ns:
+  spi-cs-setup-delay-ns:
     description:
-      Delay in nanosecods to be introduced by the controller after CS is
+      Delay in nanoseconds to be introduced by the controller after CS is
       asserted.
 
   spi-rx-bus-width: