dt-bindings: sram: Document reg-io-width property

Some SRAMs need to be accessed with a specific access width, define
the 'reg-io-width' property specifying such access sizes.

Reviewed-by: Krzysztof Kozlowski <[email protected]>
Signed-off-by: Florian Fainelli <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Sudeep Holla <[email protected]>

Author: ffainelli

Documentation/devicetree/bindings/sram/sram.yaml

@@ -101,6 +101,12 @@ patternProperties:
           IO mem address range, relative to the SRAM range.
         maxItems: 1
 
+      reg-io-width:
+        description:
+          The size (in bytes) of the IO accesses that should be performed on the
+          SRAM.
+        enum: [1, 2, 4, 8]
+
       pool:
         description:
           Indicates that the particular reserved SRAM area is addressable