dt-bindings: nvmem: Add missing 'reg' property

With 'unevaluatedProperties' support implemented, the following warnings
are generated in the nvmem examples:

Documentation/devicetree/bindings/nvmem/st,stm32-romem.example.dt.yaml: efuse@1fff7800: Unevaluated properties are not allowed ('reg' was unexpected)
Documentation/devicetree/bindings/nvmem/rmem.example.dt.yaml: nvram@10000000: Unevaluated properties are not allowed ('reg' was unexpected)
Documentation/devicetree/bindings/nvmem/brcm,nvram.example.dt.yaml: nvram@1eff0000: Unevaluated properties are not allowed ('reg' was unexpected)

Add the missing 'reg' property definition.

Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Rafał Miłecki <rafal@milecki.pl>
Cc: Saenz Julienne <nsaenzjulienne@suse.de>
Cc: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Cc: linux-stm32@st-md-mailman.stormreply.com
Cc: linux-arm-kernel@lists.infradead.org
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20211209174235.14049-5-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/nvmem/brcm,nvram.yaml

@@ -24,6 +24,9 @@ properties:
   compatible:
     const: brcm,nvram
 
+  reg:
+    maxItems: 1
+
 unevaluatedProperties: false
 
 examples:

Documentation/devicetree/bindings/nvmem/rmem.yaml

@@ -19,6 +19,9 @@ properties:
           - raspberrypi,bootloader-config
       - const: nvmem-rmem
 
+  reg:
+    maxItems: 1
+
   no-map:
     $ref: /schemas/types.yaml#/definitions/flag
     description:

Documentation/devicetree/bindings/nvmem/st,stm32-romem.yaml

@@ -24,6 +24,9 @@ properties:
       - st,stm32f4-otp
       - st,stm32mp15-bsec
 
+  reg:
+    maxItems: 1
+
 patternProperties:
   "^.*@[0-9a-f]+$":
     type: object