dt-bindings: serial: pl011: Add a reg-io-width parameter

Some of the implementations support only 32-bit accesses.
Add a parameter reg-io-width for such platforms.
Reviewed-by: NKrzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: NShubhrajyoti Datta <shubhrajyoti.datta@amd.com>
Link: https://lore.kernel.org/r/20220826120559.2122-2-shubhrajyoti.datta@amd.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/pl011.yaml

@@ -94,6 +94,12 @@ properties:
   resets:
     maxItems: 1
 
+  reg-io-width:
+    description:
+      The size (in bytes) of the IO accesses that should be performed
+      on the device.
+    enum: [1, 4]
+
 required:
   - compatible
   - reg