dt-bindings: mfd: mc13xxx: Remove obsolete property

The 'fsl,spi-num-chipselects' property is obsolete according to
Documentation/devicetree/bindings/spi/fsl-imx-cspi.txt, so remove
it from the example.
Signed-off-by: NFabio Estevam <fabio.estevam@nxp.com>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

Documentation/devicetree/bindings/mfd/mc13xxx.txt

@@ -113,7 +113,6 @@ MC13892 regulators:
 Examples:
 
 ecspi@70010000 { /* ECSPI1 */
-	fsl,spi-num-chipselects = <2>;
 	cs-gpios = <&gpio4 24 0>, /* GPIO4_24 */
 		   <&gpio4 25 0>; /* GPIO4_25 */