spi: Use 'flash' node name instead of 'spi-flash' in example

Change the nodename in the example with spi-nand from 'spi-flash@1'
to 'flash@1' to make the schema uniform with both spi-nand and spi-nor
flashes. jedec,spi-nor.yaml uses 'flash@' nodename for spi-nor flashes,
so make the spi-nand examples in dt-bindings use it too for uniformity.
Signed-off-by: Apurva Nandan <a-nandan@ti.com>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210920142713.129295-3-a-nandan@ti.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml

@@ -171,7 +171,7 @@ examples:
       cs-gpios = <&gpio0 13 0>,
                  <&gpio0 14 0>;
       rx-sample-delay-ns = <3>;
-      spi-flash@1 {
+      flash@1 {
         compatible = "spi-nand";
         reg = <1>;
         rx-sample-delay-ns = <7>;