dt-bindings: nvmem: convert base example to use NVMEM fixed cells layout

With support for the "fixed-layout" binding it's possible and preferred
now to define fixed NVMEM cells in the layout node. Do that for the
binding example binding.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

Documentation/devicetree/bindings/nvmem/nvmem.yaml

@@ -68,24 +68,30 @@ examples:
 
           /* ... */
 
-          /* Data cells */
-          tsens_calibration: calib@404 {
-              reg = <0x404 0x10>;
-          };
-
-          tsens_calibration_bckp: calib_bckp@504 {
-              reg = <0x504 0x11>;
-              bits = <6 128>;
-          };
-
-          pvs_version: pvs-version@6 {
-              reg = <0x6 0x2>;
-              bits = <7 2>;
-          };
-
-          speed_bin: speed-bin@c{
-              reg = <0xc 0x1>;
-              bits = <2 3>;
+          nvmem-layout {
+              compatible = "fixed-layout";
+              #address-cells = <1>;
+              #size-cells = <1>;
+
+              /* Data cells */
+              tsens_calibration: calib@404 {
+                  reg = <0x404 0x10>;
+              };
+
+              tsens_calibration_bckp: calib_bckp@504 {
+                  reg = <0x504 0x11>;
+                  bits = <6 128>;
+              };
+
+              pvs_version: pvs-version@6 {
+                  reg = <0x6 0x2>;
+                  bits = <7 2>;
+              };
+
+              speed_bin: speed-bin@c{
+                  reg = <0xc 0x1>;
+                  bits = <2 3>;
+              };
           };
       };