dt-bindings: mtd: st,spear600-smi: Fix example

Example is wrong, the reg property of the flash is always matching the
node name.

Fixes: 68cd8ef ("dt-bindings: mtd: st,spear600-smi: convert to DT schema")
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Author: miquelraynal

Documentation/devicetree/bindings/mtd/st,spear600-smi.yaml

@@ -76,7 +76,7 @@ examples:
         interrupts = <12>;
         clock-rate = <50000000>;  /* 50 MHz */
 
-        flash@f8000000 {
+        flash@fc000000 {
             reg = <0xfc000000 0x1000>;
             st,smi-fast-mode;
         };